diff --git a/src/applications/harbormaster/application/PhabricatorApplicationHarbormaster.php b/src/applications/harbormaster/application/PhabricatorApplicationHarbormaster.php
--- a/src/applications/harbormaster/application/PhabricatorApplicationHarbormaster.php
+++ b/src/applications/harbormaster/application/PhabricatorApplicationHarbormaster.php
@@ -50,6 +50,8 @@
           => 'HarbormasterBuildableListController',
         'step/' => array(
           'add/(?:(?P<id>\d+)/)?' => 'HarbormasterStepAddController',
+          'new/(?P<plan>\d+)/(?P<class>[^/]+)/'
+            => 'HarbormasterStepEditController',
           'edit/(?:(?P<id>\d+)/)?' => 'HarbormasterStepEditController',
           'delete/(?:(?P<id>\d+)/)?' => 'HarbormasterStepDeleteController',
         ),
diff --git a/src/applications/harbormaster/controller/HarbormasterStepAddController.php b/src/applications/harbormaster/controller/HarbormasterStepAddController.php
--- a/src/applications/harbormaster/controller/HarbormasterStepAddController.php
+++ b/src/applications/harbormaster/controller/HarbormasterStepAddController.php
@@ -16,47 +16,32 @@
     $this->requireApplicationCapability(
       HarbormasterCapabilityManagePlans::CAPABILITY);
 
-    $id = $this->id;
-
     $plan = id(new HarbormasterBuildPlanQuery())
         ->setViewer($viewer)
-        ->withIDs(array($id))
+        ->withIDs(array($this->id))
         ->executeOne();
     if (!$plan) {
       return new Aphront404Response();
     }
 
-    $cancel_uri = $this->getApplicationURI('plan/'.$plan->getID().'/');
+    $plan_id = $plan->getID();
+    $cancel_uri = $this->getApplicationURI("plan/{$plan_id}/");
 
-    if ($request->isDialogFormPost()) {
-      $class = $request->getStr('step-type');
+    $errors = array();
+    if ($request->isFormPost()) {
+      $class = $request->getStr('class');
       if (!HarbormasterBuildStepImplementation::getImplementation($class)) {
-        return $this->createDialog($cancel_uri);
+        $errors[] = pht(
+          'Choose the type of build step you want to add.');
+      }
+      if (!$errors) {
+        $new_uri = $this->getApplicationURI("step/new/{$plan_id}/{$class}/");
+        return id(new AphrontRedirectResponse())->setURI($new_uri);
       }
-
-      $steps = $plan->loadOrderedBuildSteps();
-
-      $step = new HarbormasterBuildStep();
-      $step->setBuildPlanPHID($plan->getPHID());
-      $step->setClassName($class);
-      $step->setDetails(array());
-      $step->setSequence(count($steps) + 1);
-      $step->save();
-
-      $edit_uri = $this->getApplicationURI("step/edit/".$step->getID()."/");
-
-      return id(new AphrontRedirectResponse())->setURI($edit_uri);
     }
 
-    return $this->createDialog($cancel_uri);
-  }
-
-  private function createDialog($cancel_uri) {
-    $request = $this->getRequest();
-    $viewer = $request->getUser();
-
     $control = id(new AphrontFormRadioButtonControl())
-      ->setName('step-type');
+      ->setName('class');
 
     $all = HarbormasterBuildStepImplementation::getImplementations();
     foreach ($all as $class => $implementation) {
@@ -66,10 +51,16 @@
         $implementation->getGenericDescription());
     }
 
+    if ($errors) {
+      $errors = id(new AphrontErrorView())
+        ->setErrors($errors);
+    }
+
     return $this->newDialog()
       ->setTitle(pht('Add New Step'))
       ->addSubmitButton(pht('Add Build Step'))
       ->addCancelButton($cancel_uri)
+      ->appendChild($errors)
       ->appendParagraph(pht('Choose a type of build step to add:'))
       ->appendChild($control);
   }
diff --git a/src/applications/harbormaster/controller/HarbormasterStepEditController.php b/src/applications/harbormaster/controller/HarbormasterStepEditController.php
--- a/src/applications/harbormaster/controller/HarbormasterStepEditController.php
+++ b/src/applications/harbormaster/controller/HarbormasterStepEditController.php
@@ -4,9 +4,13 @@
   extends HarbormasterController {
 
   private $id;
+  private $planID;
+  private $className;
 
   public function willProcessRequest(array $data) {
     $this->id = idx($data, 'id');
+    $this->planID = idx($data, 'plan');
+    $this->className = idx($data, 'class');
   }
 
   public function processRequest() {
@@ -16,15 +20,40 @@
     $this->requireApplicationCapability(
       HarbormasterCapabilityManagePlans::CAPABILITY);
 
-    $step = id(new HarbormasterBuildStepQuery())
-      ->setViewer($viewer)
-      ->withIDs(array($this->id))
-      ->executeOne();
-    if (!$step) {
-      return new Aphront404Response();
+    if ($this->id) {
+      $step = id(new HarbormasterBuildStepQuery())
+        ->setViewer($viewer)
+        ->withIDs(array($this->id))
+        ->executeOne();
+      if (!$step) {
+        return new Aphront404Response();
+      }
+      $plan = $step->getBuildPlan();
+
+      $is_new = false;
+    } else {
+      $plan = id(new HarbormasterBuildPlanQuery())
+          ->setViewer($viewer)
+          ->withIDs(array($this->planID))
+          ->executeOne();
+      if (!$plan) {
+        return new Aphront404Response();
+      }
+
+      $impl = HarbormasterBuildStepImplementation::getImplementation(
+        $this->className);
+      if (!$impl) {
+        return new Aphront404Response();
+      }
+
+      $step = HarbormasterBuildStep::initializeNewStep($viewer)
+        ->setBuildPlanPHID($plan->getPHID())
+        ->setClassName($this->className);
+
+      $is_new = true;
     }
 
-    $plan = $step->getBuildPlan();
+    $plan_uri = $this->getApplicationURI('plan/'.$plan->getID().'/');
 
     $implementation = $step->getStepImplementation();
 
@@ -47,10 +76,16 @@
         ->setContinueOnNoEffect(true)
         ->setContentSourceFromRequest($request);
 
+      if ($is_new) {
+        // This is okay, but a little iffy. We should move it inside the editor
+        // if we create plans elsewhere.
+        $steps = $plan->loadOrderedBuildSteps();
+        $step->setSequence(count($steps) + 1);
+      }
+
       try {
         $editor->applyTransactions($step, $xactions);
-        return id(new AphrontRedirectResponse())
-          ->setURI($this->getApplicationURI('plan/'.$plan->getID().'/'));
+        return id(new AphrontRedirectResponse())->setURI($plan_uri);
       } catch (PhabricatorApplicationTransactionValidationException $ex) {
         $validation_exception = $ex;
       }
@@ -61,36 +96,47 @@
 
     $field_list->appendFieldsToForm($form);
 
+    if ($is_new) {
+      $submit = pht('Create Build Step');
+      $header = pht('New Step: %s', $implementation->getName());
+      $crumb = pht('Add Step');
+    } else {
+      $submit = pht('Save Build Step');
+      $header = pht('Edit Step: %s', $implementation->getName());
+      $crumb = pht('Edit Step');
+    }
+
     $form->appendChild(
       id(new AphrontFormSubmitControl())
-        ->setValue(pht('Save Build Step'))
-        ->addCancelButton(
-          $this->getApplicationURI('plan/'.$plan->getID().'/')));
+        ->setValue($submit)
+        ->addCancelButton($plan_uri));
 
     $box = id(new PHUIObjectBoxView())
-      ->setHeaderText('Edit Step: '.$implementation->getName())
+      ->setHeaderText($header)
       ->setValidationException($validation_exception)
       ->setForm($form);
 
     $crumbs = $this->buildApplicationCrumbs();
     $id = $plan->getID();
-    $crumbs->addTextCrumb(
-      pht("Plan %d", $id),
-      $this->getApplicationURI("plan/{$id}/"));
-    $crumbs->addTextCrumb(pht('Edit Step'));
+    $crumbs->addTextCrumb(pht('Plan %d', $id), $plan_uri);
+    $crumbs->addTextCrumb($crumb);
 
     $variables = $this->renderBuildVariablesTable();
 
-    $xactions = id(new HarbormasterBuildStepTransactionQuery())
-      ->setViewer($viewer)
-      ->withObjectPHIDs(array($step->getPHID()))
-      ->execute();
-
-    $xaction_view = id(new PhabricatorApplicationTransactionView())
-      ->setUser($viewer)
-      ->setObjectPHID($step->getPHID())
-      ->setTransactions($xactions)
-      ->setShouldTerminate(true);
+    if ($is_new) {
+      $xaction_view = null;
+    } else {
+      $xactions = id(new HarbormasterBuildStepTransactionQuery())
+        ->setViewer($viewer)
+        ->withObjectPHIDs(array($step->getPHID()))
+        ->execute();
+
+      $xaction_view = id(new PhabricatorApplicationTransactionView())
+        ->setUser($viewer)
+        ->setObjectPHID($step->getPHID())
+        ->setTransactions($xactions)
+        ->setShouldTerminate(true);
+    }
 
     return $this->buildApplicationPage(
       array(
diff --git a/src/applications/harbormaster/storage/configuration/HarbormasterBuildStep.php b/src/applications/harbormaster/storage/configuration/HarbormasterBuildStep.php
--- a/src/applications/harbormaster/storage/configuration/HarbormasterBuildStep.php
+++ b/src/applications/harbormaster/storage/configuration/HarbormasterBuildStep.php
@@ -14,6 +14,10 @@
   private $customFields = self::ATTACHABLE;
   private $implementation;
 
+  public static function initializeNewStep(PhabricatorUser $actor) {
+    return id(new HarbormasterBuildStep());
+  }
+
   public function getConfiguration() {
     return array(
       self::CONFIG_AUX_PHID => true,