diff --git a/resources/sql/autopatches/20150601.spaces.1.namespace.sql b/resources/sql/autopatches/20150601.spaces.1.namespace.sql
new file mode 100644
--- /dev/null
+++ b/resources/sql/autopatches/20150601.spaces.1.namespace.sql
@@ -0,0 +1,12 @@
+CREATE TABLE {$NAMESPACE}_spaces.spaces_namespace (
+  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  phid VARBINARY(64) NOT NULL,
+  namespaceName VARCHAR(255) NOT NULL COLLATE {$COLLATE_TEXT},
+  viewPolicy VARBINARY(64) NOT NULL,
+  editPolicy VARBINARY(64) NOT NULL,
+  isDefaultNamespace BOOL,
+  dateCreated INT UNSIGNED NOT NULL,
+  dateModified INT UNSIGNED NOT NULL,
+  UNIQUE KEY `key_phid` (phid),
+  UNIQUE KEY `key_default` (isDefaultNamespace)
+) ENGINE=InnoDB, COLLATE {$COLLATE_TEXT};
diff --git a/resources/sql/autopatches/20150601.spaces.2.xaction.sql b/resources/sql/autopatches/20150601.spaces.2.xaction.sql
new file mode 100644
--- /dev/null
+++ b/resources/sql/autopatches/20150601.spaces.2.xaction.sql
@@ -0,0 +1,19 @@
+CREATE TABLE {$NAMESPACE}_spaces.spaces_namespacetransaction (
+  id INT UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT,
+  phid VARBINARY(64) NOT NULL,
+  authorPHID VARBINARY(64) NOT NULL,
+  objectPHID VARBINARY(64) NOT NULL,
+  viewPolicy VARBINARY(64) NOT NULL,
+  editPolicy VARBINARY(64) NOT NULL,
+  commentPHID VARBINARY(64),
+  commentVersion INT UNSIGNED NOT NULL,
+  transactionType VARCHAR(32) NOT NULL COLLATE {$COLLATE_TEXT},
+  oldValue LONGTEXT NOT NULL COLLATE {$COLLATE_TEXT},
+  newValue LONGTEXT NOT NULL COLLATE {$COLLATE_TEXT},
+  contentSource LONGTEXT NOT NULL COLLATE {$COLLATE_TEXT},
+  metadata LONGTEXT NOT NULL COLLATE {$COLLATE_TEXT},
+  dateCreated INT UNSIGNED NOT NULL,
+  dateModified INT UNSIGNED NOT NULL,
+  UNIQUE KEY `key_phid` (phid),
+  KEY `key_object` (objectPHID)
+) ENGINE=InnoDB, COLLATE {$COLLATE_TEXT};
diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -1318,6 +1318,7 @@
     'PhabricatorApplicationSearchController' => 'applications/search/controller/PhabricatorApplicationSearchController.php',
     'PhabricatorApplicationSearchEngine' => 'applications/search/engine/PhabricatorApplicationSearchEngine.php',
     'PhabricatorApplicationSearchResultsControllerInterface' => 'applications/search/interface/PhabricatorApplicationSearchResultsControllerInterface.php',
+    'PhabricatorApplicationSpaces' => 'applications/spaces/application/PhabricatorApplicationSpaces.php',
     'PhabricatorApplicationStatusView' => 'applications/meta/view/PhabricatorApplicationStatusView.php',
     'PhabricatorApplicationTransaction' => 'applications/transactions/storage/PhabricatorApplicationTransaction.php',
     'PhabricatorApplicationTransactionComment' => 'applications/transactions/storage/PhabricatorApplicationTransactionComment.php',
@@ -2561,6 +2562,22 @@
     'PhabricatorSlugTestCase' => 'infrastructure/util/__tests__/PhabricatorSlugTestCase.php',
     'PhabricatorSortTableUIExample' => 'applications/uiexample/examples/PhabricatorSortTableUIExample.php',
     'PhabricatorSourceCodeView' => 'view/layout/PhabricatorSourceCodeView.php',
+    'PhabricatorSpacesCapabilityCreateSpaces' => 'applications/spaces/capability/PhabricatorSpacesCapabilityCreateSpaces.php',
+    'PhabricatorSpacesCapabilityDefaultEdit' => 'applications/spaces/capability/PhabricatorSpacesCapabilityDefaultEdit.php',
+    'PhabricatorSpacesCapabilityDefaultView' => 'applications/spaces/capability/PhabricatorSpacesCapabilityDefaultView.php',
+    'PhabricatorSpacesController' => 'applications/spaces/controller/PhabricatorSpacesController.php',
+    'PhabricatorSpacesDAO' => 'applications/spaces/storage/PhabricatorSpacesDAO.php',
+    'PhabricatorSpacesEditController' => 'applications/spaces/controller/PhabricatorSpacesEditController.php',
+    'PhabricatorSpacesInterface' => 'applications/spaces/interface/PhabricatorSpacesInterface.php',
+    'PhabricatorSpacesListController' => 'applications/spaces/controller/PhabricatorSpacesListController.php',
+    'PhabricatorSpacesNamespace' => 'applications/spaces/storage/PhabricatorSpacesNamespace.php',
+    'PhabricatorSpacesNamespaceEditor' => 'applications/spaces/editor/PhabricatorSpacesNamespaceEditor.php',
+    'PhabricatorSpacesNamespacePHIDType' => 'applications/spaces/phid/PhabricatorSpacesNamespacePHIDType.php',
+    'PhabricatorSpacesNamespaceQuery' => 'applications/spaces/query/PhabricatorSpacesNamespaceQuery.php',
+    'PhabricatorSpacesNamespaceSearchEngine' => 'applications/spaces/query/PhabricatorSpacesNamespaceSearchEngine.php',
+    'PhabricatorSpacesNamespaceTransaction' => 'applications/spaces/storage/PhabricatorSpacesNamespaceTransaction.php',
+    'PhabricatorSpacesNamespaceTransactionQuery' => 'applications/spaces/query/PhabricatorSpacesNamespaceTransactionQuery.php',
+    'PhabricatorSpacesViewController' => 'applications/spaces/controller/PhabricatorSpacesViewController.php',
     'PhabricatorStandardCustomField' => 'infrastructure/customfield/standard/PhabricatorStandardCustomField.php',
     'PhabricatorStandardCustomFieldBool' => 'infrastructure/customfield/standard/PhabricatorStandardCustomFieldBool.php',
     'PhabricatorStandardCustomFieldCredential' => 'infrastructure/customfield/standard/PhabricatorStandardCustomFieldCredential.php',
@@ -4647,6 +4664,7 @@
     'PhabricatorApplicationPanelController' => 'PhabricatorApplicationsController',
     'PhabricatorApplicationQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
     'PhabricatorApplicationSearchController' => 'PhabricatorSearchBaseController',
+    'PhabricatorApplicationSpaces' => 'PhabricatorApplication',
     'PhabricatorApplicationStatusView' => 'AphrontView',
     'PhabricatorApplicationTransaction' => array(
       'PhabricatorLiskDAO',
@@ -6027,6 +6045,26 @@
     'PhabricatorSlugTestCase' => 'PhabricatorTestCase',
     'PhabricatorSortTableUIExample' => 'PhabricatorUIExample',
     'PhabricatorSourceCodeView' => 'AphrontView',
+    'PhabricatorSpacesCapabilityCreateSpaces' => 'PhabricatorPolicyCapability',
+    'PhabricatorSpacesCapabilityDefaultEdit' => 'PhabricatorPolicyCapability',
+    'PhabricatorSpacesCapabilityDefaultView' => 'PhabricatorPolicyCapability',
+    'PhabricatorSpacesController' => 'PhabricatorController',
+    'PhabricatorSpacesDAO' => 'PhabricatorLiskDAO',
+    'PhabricatorSpacesEditController' => 'PhabricatorSpacesController',
+    'PhabricatorSpacesInterface' => 'PhabricatorPHIDInterface',
+    'PhabricatorSpacesListController' => 'PhabricatorSpacesController',
+    'PhabricatorSpacesNamespace' => array(
+      'PhabricatorSpacesDAO',
+      'PhabricatorPolicyInterface',
+      'PhabricatorApplicationTransactionInterface',
+    ),
+    'PhabricatorSpacesNamespaceEditor' => 'PhabricatorApplicationTransactionEditor',
+    'PhabricatorSpacesNamespacePHIDType' => 'PhabricatorPHIDType',
+    'PhabricatorSpacesNamespaceQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
+    'PhabricatorSpacesNamespaceSearchEngine' => 'PhabricatorApplicationSearchEngine',
+    'PhabricatorSpacesNamespaceTransaction' => 'PhabricatorApplicationTransaction',
+    'PhabricatorSpacesNamespaceTransactionQuery' => 'PhabricatorApplicationTransactionQuery',
+    'PhabricatorSpacesViewController' => 'PhabricatorSpacesController',
     'PhabricatorStandardCustomField' => 'PhabricatorCustomField',
     'PhabricatorStandardCustomFieldBool' => 'PhabricatorStandardCustomField',
     'PhabricatorStandardCustomFieldCredential' => 'PhabricatorStandardCustomField',
diff --git a/src/applications/spaces/application/PhabricatorApplicationSpaces.php b/src/applications/spaces/application/PhabricatorApplicationSpaces.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/application/PhabricatorApplicationSpaces.php
@@ -0,0 +1,67 @@
+<?php
+
+final class PhabricatorApplicationSpaces extends PhabricatorApplication {
+
+  public function getBaseURI() {
+    return '/spaces/';
+  }
+
+  public function getName() {
+    return pht('Spaces');
+  }
+
+  public function getShortDescription() {
+    return pht('Policy Namespaces');
+  }
+
+  public function getFontIcon() {
+    return 'fa-compass';
+  }
+
+  public function getTitleGlyph() {
+    return "\xE2\x97\x8B";
+  }
+
+  public function getFlavorText() {
+    return pht('Control access to groups of objects.');
+  }
+
+  public function getApplicationGroup() {
+    return self::GROUP_UTILITIES;
+  }
+
+  public function canUninstall() {
+    return true;
+  }
+
+  public function isPrototype() {
+    return true;
+  }
+
+  public function getRoutes() {
+    return array(
+      '/S(?P<id>[1-9]\d*)' => 'PhabricatorSpacesViewController',
+      '/spaces/' => array(
+        '(?:query/(?P<queryKey>[^/]+)/)?' => 'PhabricatorSpacesListController',
+        'create/' => 'PhabricatorSpacesEditController',
+        'edit/(?:(?P<id>\d+)/)?' => 'PhabricatorSpacesEditController',
+      ),
+    );
+  }
+
+  protected function getCustomCapabilities() {
+    return array(
+      PhabricatorSpacesCapabilityCreateSpaces::CAPABILITY => array(
+        'default' => PhabricatorPolicies::POLICY_ADMIN,
+      ),
+      PhabricatorSpacesCapabilityDefaultView::CAPABILITY => array(
+        'caption' => pht('Default view policy for newly created spaces.'),
+      ),
+      PhabricatorSpacesCapabilityDefaultEdit::CAPABILITY => array(
+        'caption' => pht('Default edit policy for newly created spaces.'),
+        'default' => PhabricatorPolicies::POLICY_ADMIN,
+      ),
+    );
+  }
+
+}
diff --git a/src/applications/spaces/capability/PhabricatorSpacesCapabilityCreateSpaces.php b/src/applications/spaces/capability/PhabricatorSpacesCapabilityCreateSpaces.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/capability/PhabricatorSpacesCapabilityCreateSpaces.php
@@ -0,0 +1,16 @@
+<?php
+
+final class PhabricatorSpacesCapabilityCreateSpaces
+  extends PhabricatorPolicyCapability {
+
+  const CAPABILITY = 'spaces.create';
+
+  public function getCapabilityName() {
+    return pht('Can Create Spaces');
+  }
+
+  public function describeCapabilityRejection() {
+    return pht('You do not have permission to create spaces.');
+  }
+
+}
diff --git a/src/applications/spaces/capability/PhabricatorSpacesCapabilityDefaultEdit.php b/src/applications/spaces/capability/PhabricatorSpacesCapabilityDefaultEdit.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/capability/PhabricatorSpacesCapabilityDefaultEdit.php
@@ -0,0 +1,12 @@
+<?php
+
+final class PhabricatorSpacesCapabilityDefaultEdit
+  extends PhabricatorPolicyCapability {
+
+  const CAPABILITY = 'spaces.default.edit';
+
+  public function getCapabilityName() {
+    return pht('Default Edit Policy');
+  }
+
+}
diff --git a/src/applications/spaces/capability/PhabricatorSpacesCapabilityDefaultView.php b/src/applications/spaces/capability/PhabricatorSpacesCapabilityDefaultView.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/capability/PhabricatorSpacesCapabilityDefaultView.php
@@ -0,0 +1,16 @@
+<?php
+
+final class PhabricatorSpacesCapabilityDefaultView
+  extends PhabricatorPolicyCapability {
+
+  const CAPABILITY = 'spaces.default.view';
+
+  public function getCapabilityName() {
+    return pht('Default View Policy');
+  }
+
+  public function shouldAllowPublicPolicySetting() {
+    return true;
+  }
+
+}
diff --git a/src/applications/spaces/controller/PhabricatorSpacesController.php b/src/applications/spaces/controller/PhabricatorSpacesController.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/controller/PhabricatorSpacesController.php
@@ -0,0 +1,3 @@
+<?php
+
+abstract class PhabricatorSpacesController extends PhabricatorController {}
diff --git a/src/applications/spaces/controller/PhabricatorSpacesEditController.php b/src/applications/spaces/controller/PhabricatorSpacesEditController.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/controller/PhabricatorSpacesEditController.php
@@ -0,0 +1,174 @@
+<?php
+
+final class PhabricatorSpacesEditController
+  extends PhabricatorSpacesController {
+
+  public function handleRequest(AphrontRequest $request) {
+    $viewer = $request->getUser();
+
+    $make_default = false;
+
+    $id = $request->getURIData('id');
+    if ($id) {
+      $space = id(new PhabricatorSpacesNamespaceQuery())
+        ->setViewer($viewer)
+        ->withIDs(array($id))
+        ->requireCapabilities(
+          array(
+            PhabricatorPolicyCapability::CAN_VIEW,
+            PhabricatorPolicyCapability::CAN_EDIT,
+          ))
+        ->executeOne();
+      if (!$space) {
+        return new Aphront404Response();
+      }
+
+      $is_new = false;
+      $cancel_uri = '/'.$space->getMonogram();
+
+      $header_text = pht('Edit %s', $space->getNamespaceName());
+      $title = pht('Edit Space');
+      $button_text = pht('Save Changes');
+    } else {
+      $this->requireApplicationCapability(
+        PhabricatorSpacesCapabilityCreateSpaces::CAPABILITY);
+
+      $space = PhabricatorSpacesNamespace::initializeNewNamespace($viewer);
+
+      $is_new = true;
+      $cancel_uri = $this->getApplicationURI();
+
+      $header_text = pht('Create Space');
+      $title = pht('Create Space');
+      $button_text = pht('Create Space');
+
+      $default = id(new PhabricatorSpacesNamespaceQuery())
+        ->setViewer(PhabricatorUser::getOmnipotentUser())
+        ->withIsDefaultNamespace(true)
+        ->execute();
+      if (!$default) {
+        $make_default = true;
+      }
+    }
+
+    $validation_exception = null;
+    $e_name = true;
+    $v_name = $space->getNamespaceName();
+    $v_view = $space->getViewPolicy();
+    $v_edit = $space->getEditPolicy();
+
+    if ($request->isFormPost()) {
+      $xactions = array();
+      $e_name = null;
+
+      $v_name = $request->getStr('name');
+      $v_view = $request->getStr('viewPolicy');
+      $v_edit = $request->getStr('editPolicy');
+
+      $type_name = PhabricatorSpacesNamespaceTransaction::TYPE_NAME;
+      $type_default = PhabricatorSpacesNamespaceTransaction::TYPE_DEFAULT;
+      $type_view = PhabricatorTransactions::TYPE_VIEW_POLICY;
+      $type_edit = PhabricatorTransactions::TYPE_EDIT_POLICY;
+
+      $xactions[] = id(new PhabricatorSpacesNamespaceTransaction())
+        ->setTransactionType($type_name)
+        ->setNewValue($v_name);
+
+      $xactions[] = id(new PhabricatorSpacesNamespaceTransaction())
+        ->setTransactionType($type_view)
+        ->setNewValue($v_view);
+
+      $xactions[] = id(new PhabricatorSpacesNamespaceTransaction())
+        ->setTransactionType($type_edit)
+        ->setNewValue($v_edit);
+
+      if ($make_default) {
+        $xactions[] = id(new PhabricatorSpacesNamespaceTransaction())
+          ->setTransactionType($type_default)
+          ->setNewValue(1);
+      }
+
+      $editor = id(new PhabricatorSpacesNamespaceEditor())
+        ->setActor($viewer)
+        ->setContinueOnNoEffect(true)
+        ->setContentSourceFromRequest($request);
+
+      try {
+        $editor->applyTransactions($space, $xactions);
+
+        return id(new AphrontRedirectResponse())
+          ->setURI('/'.$space->getMonogram());
+      } catch (PhabricatorApplicationTransactionValidationException $ex) {
+        $validation_exception = $ex;
+
+        $e_name = $ex->getShortMessage($type_name);
+      }
+    }
+
+    $policies = id(new PhabricatorPolicyQuery())
+      ->setViewer($viewer)
+      ->setObject($space)
+      ->execute();
+
+    $form = id(new AphrontFormView())
+      ->setUser($viewer);
+
+    if ($make_default) {
+      $form->appendRemarkupInstructions(
+        pht(
+          'NOTE: You are creating the **default space**. All existing '.
+          'objects will be put into this space. You must create a default '.
+          'space before you can create other spaces.'));
+    }
+
+    $form
+      ->appendChild(
+        id(new AphrontFormTextControl())
+          ->setLabel(pht('Name'))
+          ->setName('name')
+          ->setValue($v_name)
+          ->setError($e_name))
+      ->appendChild(
+        id(new AphrontFormPolicyControl())
+          ->setUser($viewer)
+          ->setCapability(PhabricatorPolicyCapability::CAN_VIEW)
+          ->setPolicyObject($space)
+          ->setPolicies($policies)
+          ->setValue($v_view)
+          ->setName('viewPolicy'))
+      ->appendChild(
+        id(new AphrontFormPolicyControl())
+          ->setUser($viewer)
+          ->setCapability(PhabricatorPolicyCapability::CAN_EDIT)
+          ->setPolicyObject($space)
+          ->setPolicies($policies)
+          ->setValue($v_edit)
+          ->setName('editPolicy'))
+      ->appendChild(
+        id(new AphrontFormSubmitControl())
+          ->setValue($button_text)
+          ->addCancelButton($cancel_uri));
+
+    $box = id(new PHUIObjectBoxView())
+      ->setHeaderText($header_text)
+      ->setValidationException($validation_exception)
+      ->appendChild($form);
+
+    $crumbs = $this->buildApplicationCrumbs();
+    if (!$is_new) {
+      $crumbs->addTextCrumb(
+        $space->getMonogram(),
+        $cancel_uri);
+    }
+    $crumbs->addTextCrumb($title);
+
+    return $this->buildApplicationPage(
+      array(
+        $crumbs,
+        $box,
+      ),
+      array(
+        'title' => $title,
+      ));
+  }
+}
diff --git a/src/applications/spaces/controller/PhabricatorSpacesListController.php b/src/applications/spaces/controller/PhabricatorSpacesListController.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/controller/PhabricatorSpacesListController.php
@@ -0,0 +1,52 @@
+<?php
+
+final class PhabricatorSpacesListController
+  extends PhabricatorSpacesController {
+
+  public function shouldAllowPublic() {
+    return true;
+  }
+
+  public function handleRequest(AphrontRequest $request) {
+    $request = $this->getRequest();
+    $controller = id(new PhabricatorApplicationSearchController($request))
+      ->setQueryKey($request->getURIData('queryKey'))
+      ->setSearchEngine(new PhabricatorSpacesNamespaceSearchEngine())
+      ->setNavigation($this->buildSideNavView());
+
+    return $this->delegateToController($controller);
+  }
+
+  public function buildSideNavView($for_app = false) {
+    $user = $this->getRequest()->getUser();
+
+    $nav = new AphrontSideNavFilterView();
+    $nav->setBaseURI(new PhutilURI($this->getApplicationURI()));
+
+    id(new PhabricatorSpacesNamespaceSearchEngine())
+      ->setViewer($user)
+      ->addNavigationItems($nav->getMenu());
+
+    $nav->selectFilter(null);
+
+    return $nav;
+  }
+
+  public function buildApplicationCrumbs() {
+    $crumbs = parent::buildApplicationCrumbs();
+
+    $can_create = $this->hasApplicationCapability(
+      PhabricatorSpacesCapabilityCreateSpaces::CAPABILITY);
+
+    $crumbs->addAction(
+      id(new PHUIListItemView())
+        ->setName(pht('Create Space'))
+        ->setHref($this->getApplicationURI('create/'))
+        ->setIcon('fa-plus-square')
+        ->setDisabled(!$can_create)
+        ->setWorkflow(!$can_create));
+
+    return $crumbs;
+  }
+
+}
diff --git a/src/applications/spaces/controller/PhabricatorSpacesViewController.php b/src/applications/spaces/controller/PhabricatorSpacesViewController.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/controller/PhabricatorSpacesViewController.php
@@ -0,0 +1,104 @@
+<?php
+
+final class PhabricatorSpacesViewController
+  extends PhabricatorSpacesController {
+
+  public function shouldAllowPublic() {
+    return true;
+  }
+
+  public function handleRequest(AphrontRequest $request) {
+    $viewer = $this->getViewer();
+
+    $space = id(new PhabricatorSpacesNamespaceQuery())
+      ->setViewer($viewer)
+      ->withIDs(array($request->getURIData('id')))
+      ->executeOne();
+    if (!$space) {
+      return new Aphront404Response();
+    }
+
+    $action_list = $this->buildActionListView($space);
+    $property_list = $this->buildPropertyListView($space);
+    $property_list->setActionList($action_list);
+
+    $xactions = id(new PhabricatorSpacesNamespaceTransactionQuery())
+      ->setViewer($viewer)
+      ->withObjectPHIDs(array($space->getPHID()))
+      ->execute();
+
+    $timeline = $this->buildTransactionTimeline(
+      $space,
+      new PhabricatorSpacesNamespaceTransactionQuery());
+    $timeline->setShouldTerminate(true);
+
+    $header = id(new PHUIHeaderView())
+      ->setUser($viewer)
+      ->setHeader($space->getNamespaceName())
+      ->setPolicyObject($space);
+
+    $box = id(new PHUIObjectBoxView())
+      ->setHeader($header)
+      ->addPropertyList($property_list);
+
+    $crumbs = $this->buildApplicationCrumbs();
+    $crumbs->addTextCrumb($space->getMonogram());
+
+    return $this->buildApplicationPage(
+      array(
+        $crumbs,
+        $box,
+        $timeline,
+      ),
+      array(
+        'title' => array($space->getMonogram(), $space->getNamespaceName()),
+      ));
+  }
+
+  private function buildPropertyListView(PhabricatorSpacesNamespace $space) {
+    $viewer = $this->getRequest()->getUser();
+
+    $list = id(new PHUIPropertyListView())
+      ->setUser($viewer);
+
+    $list->addProperty(
+      pht('Default Space'),
+      $space->getIsDefaultNamespace()
+        ? pht('Yes')
+        : pht('No'));
+
+    $descriptions = PhabricatorPolicyQuery::renderPolicyDescriptions(
+      $viewer,
+      $space);
+
+    $list->addProperty(
+      pht('Editable By'),
+      $descriptions[PhabricatorPolicyCapability::CAN_EDIT]);
+
+    return $list;
+  }
+
+  private function buildActionListView(PhabricatorSpacesNamespace $space) {
+    $viewer = $this->getRequest()->getUser();
+
+    $list = id(new PhabricatorActionListView())
+      ->setUser($viewer)
+      ->setObjectURI('/'.$space->getMonogram());
+
+    $can_edit = PhabricatorPolicyFilter::hasCapability(
+      $viewer,
+      $space,
+      PhabricatorPolicyCapability::CAN_EDIT);
+
+    $list->addAction(
+      id(new PhabricatorActionView())
+        ->setName(pht('Edit Space'))
+        ->setIcon('fa-pencil')
+        ->setHref($this->getApplicationURI('edit/'.$space->getID().'/'))
+        ->setWorkflow(!$can_edit)
+        ->setDisabled(!$can_edit));
+
+    return $list;
+  }
+
+}
diff --git a/src/applications/spaces/editor/PhabricatorSpacesNamespaceEditor.php b/src/applications/spaces/editor/PhabricatorSpacesNamespaceEditor.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/editor/PhabricatorSpacesNamespaceEditor.php
@@ -0,0 +1,132 @@
+<?php
+
+final class PhabricatorSpacesNamespaceEditor
+  extends PhabricatorApplicationTransactionEditor {
+
+  public function getEditorApplicationClass() {
+    return pht('PhabricatorSpacesApplication');
+  }
+
+  public function getEditorObjectsDescription() {
+    return pht('Spaces');
+  }
+
+  public function getTransactionTypes() {
+    $types = parent::getTransactionTypes();
+
+    $types[] = PhabricatorSpacesNamespaceTransaction::TYPE_NAME;
+    $types[] = PhabricatorSpacesNamespaceTransaction::TYPE_DEFAULT;
+
+    $types[] = PhabricatorTransactions::TYPE_VIEW_POLICY;
+    $types[] = PhabricatorTransactions::TYPE_EDIT_POLICY;
+
+    return $types;
+  }
+
+  protected function getCustomTransactionOldValue(
+    PhabricatorLiskDAO $object,
+    PhabricatorApplicationTransaction $xaction) {
+
+    switch ($xaction->getTransactionType()) {
+      case PhabricatorSpacesNamespaceTransaction::TYPE_NAME:
+        $name = $object->getNamespaceName();
+        if (!strlen($name)) {
+          return null;
+        }
+        return $name;
+      case PhabricatorSpacesNamespaceTransaction::TYPE_DEFAULT:
+        return $object->getIsDefaultNamespace() ? 1 : null;
+      case PhabricatorTransactions::TYPE_VIEW_POLICY:
+        return $object->getViewPolicy();
+      case PhabricatorTransactions::TYPE_EDIT_POLICY:
+        return $object->getEditPolicy();
+    }
+
+    return parent::getCustomTransactionOldValue($object, $xaction);
+  }
+
+  protected function getCustomTransactionNewValue(
+    PhabricatorLiskDAO $object,
+    PhabricatorApplicationTransaction $xaction) {
+
+    switch ($xaction->getTransactionType()) {
+      case PhabricatorSpacesNamespaceTransaction::TYPE_NAME:
+      case PhabricatorTransactions::TYPE_VIEW_POLICY:
+      case PhabricatorTransactions::TYPE_EDIT_POLICY:
+        return $xaction->getNewValue();
+      case PhabricatorSpacesNamespaceTransaction::TYPE_DEFAULT:
+        return $xaction->getNewValue() ? 1 : null;
+    }
+
+    return parent::getCustomTransactionNewValue($object, $xaction);
+  }
+
+  protected function applyCustomInternalTransaction(
+    PhabricatorLiskDAO $object,
+    PhabricatorApplicationTransaction $xaction) {
+
+    $new = $xaction->getNewValue();
+
+    switch ($xaction->getTransactionType()) {
+      case PhabricatorSpacesNamespaceTransaction::TYPE_NAME:
+        $object->setNamespaceName($new);
+        return;
+      case PhabricatorSpacesNamespaceTransaction::TYPE_DEFAULT:
+        $object->setIsDefaultNamespace($new ? 1 : null);
+        return;
+      case PhabricatorTransactions::TYPE_VIEW_POLICY:
+        $object->setViewPolicy($new);
+        return;
+      case PhabricatorTransactions::TYPE_EDIT_POLICY:
+        $object->setEditPolicy($new);
+        return;
+    }
+
+    return parent::applyCustomInternalTransaction($object, $xaction);
+  }
+
+  protected function applyCustomExternalTransaction(
+    PhabricatorLiskDAO $object,
+    PhabricatorApplicationTransaction $xaction) {
+
+    switch ($xaction->getTransactionType()) {
+      case PhabricatorSpacesNamespaceTransaction::TYPE_NAME:
+      case PhabricatorSpacesNamespaceTransaction::TYPE_DEFAULT:
+      case PhabricatorTransactions::TYPE_VIEW_POLICY:
+      case PhabricatorTransactions::TYPE_EDIT_POLICY:
+        return;
+    }
+
+    return parent::applyCustomExternalTransaction($object, $xaction);
+  }
+
+  protected function validateTransaction(
+    PhabricatorLiskDAO $object,
+    $type,
+    array $xactions) {
+
+    $errors = parent::validateTransaction($object, $type, $xactions);
+
+    switch ($type) {
+      case PhabricatorSpacesNamespaceTransaction::TYPE_NAME:
+        $missing = $this->validateIsEmptyTextField(
+          $object->getNamespaceName(),
+          $xactions);
+
+        if ($missing) {
+          $error = new PhabricatorApplicationTransactionValidationError(
+            $type,
+            pht('Required'),
+              pht('Spaces must have a name.'),
+            nonempty(last($xactions), null));
+
+          $error->setIsMissingFieldError(true);
+          $errors[] = $error;
+        }
+        break;
+    }
+
+    return $errors;
+  }
+
+}
diff --git a/src/applications/spaces/interface/PhabricatorSpacesInterface.php b/src/applications/spaces/interface/PhabricatorSpacesInterface.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/interface/PhabricatorSpacesInterface.php
@@ -0,0 +1,3 @@
+<?php
+
+interface PhabricatorSpacesInterface extends PhabricatorPHIDInterface {}
diff --git a/src/applications/spaces/phid/PhabricatorSpacesNamespacePHIDType.php b/src/applications/spaces/phid/PhabricatorSpacesNamespacePHIDType.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/phid/PhabricatorSpacesNamespacePHIDType.php
@@ -0,0 +1,64 @@
+<?php
+
+final class PhabricatorSpacesNamespacePHIDType
+  extends PhabricatorPHIDType {
+
+  const TYPECONST = 'SPCE';
+
+  public function getTypeName() {
+    return pht('Space');
+  }
+
+  public function newObject() {
+    return new PhabricatorSpacesNamespace();
+  }
+
+  protected function buildQueryForObjects(
+    PhabricatorObjectQuery $query,
+    array $phids) {
+
+    return id(new PhabricatorSpacesNamespaceQuery())
+      ->withPHIDs($phids);
+  }
+
+  public function loadHandles(
+    PhabricatorHandleQuery $query,
+    array $handles,
+    array $objects) {
+
+    foreach ($handles as $phid => $handle) {
+      $namespace = $objects[$phid];
+      $handle->setName($namespace->getNamespaceName());
+    }
+  }
+
+  public function canLoadNamedObject($name) {
+    return preg_match('/^S[1-9]\d*$/i', $name);
+  }
+
+  public function loadNamedObjects(
+    PhabricatorObjectQuery $query,
+    array $names) {
+
+    $id_map = array();
+    foreach ($names as $name) {
+      $id = (int)substr($name, 1);
+      $id_map[$id][] = $name;
+    }
+
+    $objects = id(new PhabricatorSpacesNamespaceQuery())
+      ->setViewer($query->getViewer())
+      ->withIDs(array_keys($id_map))
+      ->execute();
+
+    $results = array();
+    foreach ($objects as $id => $object) {
+      foreach (idx($id_map, $id, array()) as $name) {
+        $results[$name] = $object;
+      }
+    }
+
+    return $results;
+  }
+
+}
diff --git a/src/applications/spaces/query/PhabricatorSpacesNamespaceQuery.php b/src/applications/spaces/query/PhabricatorSpacesNamespaceQuery.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/query/PhabricatorSpacesNamespaceQuery.php
@@ -0,0 +1,77 @@
+<?php
+
+final class PhabricatorSpacesNamespaceQuery
+  extends PhabricatorCursorPagedPolicyAwareQuery {
+
+  private $ids;
+  private $phids;
+  private $isDefaultNamespace;
+
+  public function withIDs(array $ids) {
+    $this->ids = $ids;
+    return $this;
+  }
+
+  public function withPHIDs(array $phids) {
+    $this->phids = $phids;
+    return $this;
+  }
+
+  public function withIsDefaultNamespace($default) {
+    $this->isDefaultNamespace = $default;
+    return $this;
+  }
+
+  public function getQueryApplicationClass() {
+    return 'PhabricatorApplicationSpaces';
+  }
+
+  protected function loadPage() {
+    $table = new PhabricatorSpacesNamespace();
+    $conn_r = $table->establishConnection('r');
+
+    $rows = queryfx_all(
+      $conn_r,
+      'SELECT * FROM %T %Q %Q %Q',
+      $table->getTableName(),
+      $this->buildWhereClause($conn_r),
+      $this->buildOrderClause($conn_r),
+      $this->buildLimitClause($conn_r));
+
+    return $table->loadAllFromArray($rows);
+  }
+
+  protected function buildWhereClause(AphrontDatabaseConnection $conn_r) {
+    $where = array();
+
+    if ($this->ids !== null) {
+      $where[] = qsprintf(
+        $conn_r,
+        'id IN (%Ld)',
+        $this->ids);
+    }
+
+    if ($this->phids !== null) {
+      $where[] = qsprintf(
+        $conn_r,
+        'phid IN (%Ls)',
+        $this->phids);
+    }
+
+    if ($this->isDefaultNamespace !== null) {
+      if ($this->isDefaultNamespace) {
+        $where[] = qsprintf(
+          $conn_r,
+          'isDefaultNamespace = 1');
+      } else {
+        $where[] = qsprintf(
+          $conn_r,
+          'isDefaultNamespace IS NULL');
+      }
+    }
+
+    $where[] = $this->buildPagingClause($conn_r);
+    return $this->formatWhereClause($where);
+  }
+
+}
diff --git a/src/applications/spaces/query/PhabricatorSpacesNamespaceSearchEngine.php b/src/applications/spaces/query/PhabricatorSpacesNamespaceSearchEngine.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/query/PhabricatorSpacesNamespaceSearchEngine.php
@@ -0,0 +1,81 @@
+<?php
+
+final class PhabricatorSpacesNamespaceSearchEngine
+  extends PhabricatorApplicationSearchEngine {
+
+  public function getApplicationClassName() {
+    return 'PhabricatorSpacesApplication';
+  }
+
+  public function getResultTypeDescription() {
+    return pht('Spaces');
+  }
+
+  public function buildSavedQueryFromRequest(AphrontRequest $request) {
+    $saved = new PhabricatorSavedQuery();
+
+    return $saved;
+  }
+
+  public function buildQueryFromSavedQuery(PhabricatorSavedQuery $saved) {
+    $query = id(new PhabricatorSpacesNamespaceQuery());
+
+    return $query;
+  }
+
+  public function buildSearchForm(
+    AphrontFormView $form,
+    PhabricatorSavedQuery $saved_query) {}
+
+  protected function getURI($path) {
+    return '/spaces/'.$path;
+  }
+
+  public function getBuiltinQueryNames() {
+    $names = array(
+      'all' => pht('All Spaces'),
+    );
+
+    return $names;
+  }
+
+  public function buildSavedQueryFromBuiltin($query_key) {
+
+    $query = $this->newSavedQuery();
+    $query->setQueryKey($query_key);
+
+    switch ($query_key) {
+      case 'all':
+        return $query;
+    }
+
+    return parent::buildSavedQueryFromBuiltin($query_key);
+  }
+
+  protected function renderResultList(
+    array $spaces,
+    PhabricatorSavedQuery $query,
+    array $handles) {
+    assert_instances_of($spaces, 'PhabricatorSpacesNamespace');
+
+    $viewer = $this->requireViewer();
+
+    $list = new PHUIObjectItemListView();
+    $list->setUser($viewer);
+    foreach ($spaces as $space) {
+      $item = id(new PHUIObjectItemView())
+        ->setObjectName($space->getMonogram())
+        ->setHeader($space->getNamespaceName())
+        ->setHref('/'.$space->getMonogram());
+
+      if ($space->getIsDefaultNamespace()) {
+        $item->addIcon('fa-certificate', pht('Default Space'));
+      }
+
+      $list->addItem($item);
+    }
+
+    return $list;
+  }
+
+}
diff --git a/src/applications/spaces/query/PhabricatorSpacesNamespaceTransactionQuery.php b/src/applications/spaces/query/PhabricatorSpacesNamespaceTransactionQuery.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/query/PhabricatorSpacesNamespaceTransactionQuery.php
@@ -0,0 +1,10 @@
+<?php
+
+final class PhabricatorSpacesNamespaceTransactionQuery
+  extends PhabricatorApplicationTransactionQuery {
+
+  public function getTemplateApplicationTransaction() {
+    return new PhabricatorSpacesNamespaceTransaction();
+  }
+
+}
diff --git a/src/applications/spaces/storage/PhabricatorSpacesDAO.php b/src/applications/spaces/storage/PhabricatorSpacesDAO.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/storage/PhabricatorSpacesDAO.php
@@ -0,0 +1,9 @@
+<?php
+
+abstract class PhabricatorSpacesDAO extends PhabricatorLiskDAO {
+
+  public function getApplicationName() {
+    return 'spaces';
+  }
+
+}
diff --git a/src/applications/spaces/storage/PhabricatorSpacesNamespace.php b/src/applications/spaces/storage/PhabricatorSpacesNamespace.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/storage/PhabricatorSpacesNamespace.php
@@ -0,0 +1,106 @@
+<?php
+
+final class PhabricatorSpacesNamespace
+  extends PhabricatorSpacesDAO
+  implements
+    PhabricatorPolicyInterface,
+    PhabricatorApplicationTransactionInterface {
+
+  protected $namespaceName;
+  protected $viewPolicy;
+  protected $editPolicy;
+  protected $isDefaultNamespace;
+
+  public static function initializeNewNamespace(PhabricatorUser $actor) {
+    $app = id(new PhabricatorApplicationQuery())
+      ->setViewer($actor)
+      ->withClasses(array('PhabricatorApplicationSpaces'))
+      ->executeOne();
+
+    $view_policy = $app->getPolicy(
+      PhabricatorSpacesCapabilityDefaultView::CAPABILITY);
+    $edit_policy = $app->getPolicy(
+      PhabricatorSpacesCapabilityDefaultEdit::CAPABILITY);
+
+    return id(new PhabricatorSpacesNamespace())
+      ->setIsDefaultNamespace(null)
+      ->setViewPolicy($view_policy)
+      ->setEditPolicy($edit_policy);
+  }
+
+  public function getConfiguration() {
+    return array(
+      self::CONFIG_AUX_PHID => true,
+      self::CONFIG_COLUMN_SCHEMA => array(
+        'namespaceName' => 'text255',
+        'isDefaultNamespace' => 'bool?',
+      ),
+      self::CONFIG_KEY_SCHEMA => array(
+        'key_default' => array(
+          'columns' => array('isDefaultNamespace'),
+          'unique' => true,
+        ),
+      ),
+    ) + parent::getConfiguration();
+  }
+
+  public function generatePHID() {
+    return PhabricatorPHID::generateNewPHID(
+      PhabricatorSpacesNamespacePHIDType::TYPECONST);
+  }
+
+  public function getMonogram() {
+    return 'S'.$this->getID();
+  }
+
+
+/* -(  PhabricatorPolicyInterface  )----------------------------------------- */
+
+
+  public function getCapabilities() {
+    return array(
+      PhabricatorPolicyCapability::CAN_VIEW,
+      PhabricatorPolicyCapability::CAN_EDIT,
+    );
+  }
+
+  public function getPolicy($capability) {
+    switch ($capability) {
+      case PhabricatorPolicyCapability::CAN_VIEW:
+        return $this->getViewPolicy();
+      case PhabricatorPolicyCapability::CAN_EDIT:
+        return $this->getEditPolicy();
+    }
+  }
+
+  public function hasAutomaticCapability($capability, PhabricatorUser $viewer) {
+    return false;
+  }
+
+  public function describeAutomaticCapability($capability) {
+    return null;
+  }
+
+
+/* -(  PhabricatorApplicationTransactionInterface  )------------------------- */
+
+
+  public function getApplicationTransactionEditor() {
+    return new PhabricatorSpacesNamespaceEditor();
+  }
+
+  public function getApplicationTransactionObject() {
+    return $this;
+  }
+
+  public function getApplicationTransactionTemplate() {
+    return new PhabricatorSpacesNamespaceTransaction();
+  }
+
+  public function willRenderTimeline(
+    PhabricatorApplicationTransactionView $timeline,
+    AphrontRequest $request) {
+    return $timeline;
+  }
+
+}
diff --git a/src/applications/spaces/storage/PhabricatorSpacesNamespaceTransaction.php b/src/applications/spaces/storage/PhabricatorSpacesNamespaceTransaction.php
new file mode 100644
--- /dev/null
+++ b/src/applications/spaces/storage/PhabricatorSpacesNamespaceTransaction.php
@@ -0,0 +1,49 @@
+<?php
+
+final class PhabricatorSpacesNamespaceTransaction
+  extends PhabricatorApplicationTransaction {
+
+  const TYPE_NAME = 'spaces:name';
+  const TYPE_DEFAULT = 'spaces:default';
+
+  public function getApplicationName() {
+    return 'spaces';
+  }
+
+  public function getApplicationTransactionType() {
+    return PhabricatorSpacesNamespacePHIDType::TYPECONST;
+  }
+
+  public function getApplicationTransactionCommentObject() {
+    return null;
+  }
+
+  public function getTitle() {
+    $old = $this->getOldValue();
+    $new = $this->getNewValue();
+
+    $author_phid = $this->getAuthorPHID();
+
+    switch ($this->getTransactionType()) {
+      case self::TYPE_NAME:
+        if ($old === null) {
+          return pht(
+            '%s created this space.',
+            $this->renderHandleLink($author_phid));
+        } else {
+          return pht(
+            '%s renamed this space from "%s" to "%s".',
+            $this->renderHandleLink($author_phid),
+            $old,
+            $new);
+        }
+      case self::TYPE_DEFAULT:
+        return pht(
+          '%s made this the default space.',
+          $this->renderHandleLink($author_phid));
+    }
+
+    return parent::getTitle();
+  }
+
+}
diff --git a/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php b/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php
--- a/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php
+++ b/src/infrastructure/storage/patch/PhabricatorBuiltinPatchList.php
@@ -105,6 +105,7 @@
       'db.fund' => array(),
       'db.almanac' => array(),
       'db.multimeter' => array(),
+      'db.spaces' => array(),
       '0000.legacy.sql' => array(
         'legacy' => 0,
       ),