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
@@ -4382,6 +4382,9 @@
     'PhabricatorProjectSubprojectsProfileMenuItem' => 'applications/project/menuitem/PhabricatorProjectSubprojectsProfileMenuItem.php',
     'PhabricatorProjectSubtypeDatasource' => 'applications/project/typeahead/PhabricatorProjectSubtypeDatasource.php',
     'PhabricatorProjectSubtypesConfigType' => 'applications/project/config/PhabricatorProjectSubtypesConfigType.php',
+    'PhabricatorProjectTagsAddedField' => 'applications/project/herald/PhabricatorProjectTagsAddedField.php',
+    'PhabricatorProjectTagsField' => 'applications/project/herald/PhabricatorProjectTagsField.php',
+    'PhabricatorProjectTagsRemovedField' => 'applications/project/herald/PhabricatorProjectTagsRemovedField.php',
     'PhabricatorProjectTestDataGenerator' => 'applications/project/lipsum/PhabricatorProjectTestDataGenerator.php',
     'PhabricatorProjectTransaction' => 'applications/project/storage/PhabricatorProjectTransaction.php',
     'PhabricatorProjectTransactionEditor' => 'applications/project/editor/PhabricatorProjectTransactionEditor.php',
@@ -7679,7 +7682,7 @@
     'HeraldPreCommitContentAdapter' => 'HeraldPreCommitAdapter',
     'HeraldPreCommitRefAdapter' => 'HeraldPreCommitAdapter',
     'HeraldPreventActionGroup' => 'HeraldActionGroup',
-    'HeraldProjectsField' => 'HeraldField',
+    'HeraldProjectsField' => 'PhabricatorProjectTagsField',
     'HeraldRecursiveConditionsException' => 'Exception',
     'HeraldRelatedFieldGroup' => 'HeraldFieldGroup',
     'HeraldRemarkupFieldValue' => 'HeraldFieldValue',
@@ -10943,6 +10946,9 @@
     'PhabricatorProjectSubprojectsProfileMenuItem' => 'PhabricatorProfileMenuItem',
     'PhabricatorProjectSubtypeDatasource' => 'PhabricatorTypeaheadDatasource',
     'PhabricatorProjectSubtypesConfigType' => 'PhabricatorJSONConfigType',
+    'PhabricatorProjectTagsAddedField' => 'PhabricatorProjectTagsField',
+    'PhabricatorProjectTagsField' => 'HeraldField',
+    'PhabricatorProjectTagsRemovedField' => 'PhabricatorProjectTagsField',
     'PhabricatorProjectTestDataGenerator' => 'PhabricatorTestDataGenerator',
     'PhabricatorProjectTransaction' => 'PhabricatorModularTransaction',
     'PhabricatorProjectTransactionEditor' => 'PhabricatorApplicationTransactionEditor',
diff --git a/src/applications/herald/field/HeraldField.php b/src/applications/herald/field/HeraldField.php
--- a/src/applications/herald/field/HeraldField.php
+++ b/src/applications/herald/field/HeraldField.php
@@ -241,6 +241,51 @@
     return false;
   }
 
+  final protected function getAppliedTransactionsOfTypes(array $types) {
+    $types = array_fuse($types);
+    $xactions = $this->getAdapter()->getAppliedTransactions();
+
+    $result = array();
+    foreach ($xactions as $key => $xaction) {
+      $xaction_type = $xaction->getTransactionType();
+      if (isset($types[$xaction_type])) {
+        $result[$key] = $xaction;
+      }
+    }
+
+    return $result;
+  }
+
+  final protected function getAppliedEdgeTransactionOfType($edge_type) {
+    $edge_xactions = $this->getAppliedTransactionsOfTypes(
+      array(
+        PhabricatorTransactions::TYPE_EDGE,
+      ));
+
+    $results = array();
+    foreach ($edge_xactions as $edge_xaction) {
+      $xaction_edge_type = $edge_xaction->getMetadataValue('edge:type');
+      if ($xaction_edge_type == $edge_type) {
+        $results[] = $edge_xaction;
+      }
+    }
+
+    if (count($results) > 1) {
+      throw new Exception(
+        pht(
+          'Found more than one ("%s") applied edge transactions with given '.
+          'edge type ("%s"); expected zero or one.',
+          phutil_count($results),
+          $edge_type));
+    }
+
+    if ($results) {
+      return head($results);
+    }
+
+    return null;
+  }
+
   public function isFieldAvailable() {
     return true;
   }
diff --git a/src/applications/project/herald/HeraldProjectsField.php b/src/applications/project/herald/HeraldProjectsField.php
--- a/src/applications/project/herald/HeraldProjectsField.php
+++ b/src/applications/project/herald/HeraldProjectsField.php
@@ -1,6 +1,7 @@
 <?php
 
-final class HeraldProjectsField extends HeraldField {
+final class HeraldProjectsField
+  extends PhabricatorProjectTagsField {
 
   const FIELDCONST = 'projects';
 
@@ -8,26 +9,10 @@
     return pht('Project tags');
   }
 
-  public function getFieldGroupKey() {
-    return HeraldSupportFieldGroup::FIELDGROUPKEY;
-  }
-
-  public function supportsObject($object) {
-    return ($object instanceof PhabricatorProjectInterface);
-  }
-
   public function getHeraldFieldValue($object) {
     return PhabricatorEdgeQuery::loadDestinationPHIDs(
       $object->getPHID(),
       PhabricatorProjectObjectHasProjectEdgeType::EDGECONST);
   }
 
-  protected function getHeraldFieldStandardType() {
-    return self::STANDARD_PHID_LIST;
-  }
-
-  protected function getDatasource() {
-    return new PhabricatorProjectDatasource();
-  }
-
 }
diff --git a/src/applications/project/herald/PhabricatorProjectTagsAddedField.php b/src/applications/project/herald/PhabricatorProjectTagsAddedField.php
new file mode 100644
--- /dev/null
+++ b/src/applications/project/herald/PhabricatorProjectTagsAddedField.php
@@ -0,0 +1,23 @@
+<?php
+
+final class PhabricatorProjectTagsAddedField
+  extends PhabricatorProjectTagsField {
+
+  const FIELDCONST = 'projects.added';
+
+  public function getHeraldFieldName() {
+    return pht('Project tags added');
+  }
+
+  public function getHeraldFieldValue($object) {
+    $xaction = $this->getProjectTagsTransaction();
+    if (!$xaction) {
+      return array();
+    }
+
+    $record = PhabricatorEdgeChangeRecord::newFromTransaction($xaction);
+
+    return $record->getAddedPHIDs();
+  }
+
+}
diff --git a/src/applications/project/herald/HeraldProjectsField.php b/src/applications/project/herald/PhabricatorProjectTagsField.php
copy from src/applications/project/herald/HeraldProjectsField.php
copy to src/applications/project/herald/PhabricatorProjectTagsField.php
--- a/src/applications/project/herald/HeraldProjectsField.php
+++ b/src/applications/project/herald/PhabricatorProjectTagsField.php
@@ -1,12 +1,7 @@
 <?php
 
-final class HeraldProjectsField extends HeraldField {
-
-  const FIELDCONST = 'projects';
-
-  public function getHeraldFieldName() {
-    return pht('Project tags');
-  }
+abstract class PhabricatorProjectTagsField
+  extends HeraldField {
 
   public function getFieldGroupKey() {
     return HeraldSupportFieldGroup::FIELDGROUPKEY;
@@ -16,12 +11,6 @@
     return ($object instanceof PhabricatorProjectInterface);
   }
 
-  public function getHeraldFieldValue($object) {
-    return PhabricatorEdgeQuery::loadDestinationPHIDs(
-      $object->getPHID(),
-      PhabricatorProjectObjectHasProjectEdgeType::EDGECONST);
-  }
-
   protected function getHeraldFieldStandardType() {
     return self::STANDARD_PHID_LIST;
   }
@@ -30,4 +19,9 @@
     return new PhabricatorProjectDatasource();
   }
 
+  final protected function getProjectTagsTransaction() {
+    return $this->getAppliedEdgeTransactionOfType(
+      PhabricatorProjectObjectHasProjectEdgeType::EDGECONST);
+  }
+
 }
diff --git a/src/applications/project/herald/PhabricatorProjectTagsRemovedField.php b/src/applications/project/herald/PhabricatorProjectTagsRemovedField.php
new file mode 100644
--- /dev/null
+++ b/src/applications/project/herald/PhabricatorProjectTagsRemovedField.php
@@ -0,0 +1,23 @@
+<?php
+
+final class PhabricatorProjectTagsRemovedField
+  extends PhabricatorProjectTagsField {
+
+  const FIELDCONST = 'projects.removed';
+
+  public function getHeraldFieldName() {
+    return pht('Project tags removed');
+  }
+
+  public function getHeraldFieldValue($object) {
+    $xaction = $this->getProjectTagsTransaction();
+    if (!$xaction) {
+      return array();
+    }
+
+    $record = PhabricatorEdgeChangeRecord::newFromTransaction($xaction);
+
+    return $record->getRemovedPHIDs();
+  }
+
+}