diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index e0f0209ec5..07436b6d72 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -921,6 +921,8 @@ phutil_register_library_map(array(
     'PhabricatorCustomFieldDataNotAvailableException' => 'infrastructure/customfield/exception/PhabricatorCustomFieldDataNotAvailableException.php',
     'PhabricatorCustomFieldImplementationIncompleteException' => 'infrastructure/customfield/exception/PhabricatorCustomFieldImplementationIncompleteException.php',
     'PhabricatorCustomFieldIndexStorage' => 'infrastructure/customfield/storage/PhabricatorCustomFieldIndexStorage.php',
+    'PhabricatorCustomFieldInterface' => 'infrastructure/customfield/interface/PhabricatorCustomFieldInterface.php',
+    'PhabricatorCustomFieldNotAttachedException' => 'infrastructure/customfield/exception/PhabricatorCustomFieldNotAttachedException.php',
     'PhabricatorCustomFieldNumericIndexStorage' => 'infrastructure/customfield/storage/PhabricatorCustomFieldNumericIndexStorage.php',
     'PhabricatorCustomFieldStorage' => 'infrastructure/customfield/storage/PhabricatorCustomFieldStorage.php',
     'PhabricatorCustomFieldStringIndexStorage' => 'infrastructure/customfield/storage/PhabricatorCustomFieldStringIndexStorage.php',
@@ -1541,7 +1543,7 @@ phutil_register_library_map(array(
     'PhabricatorUnitsTestCase' => 'view/__tests__/PhabricatorUnitsTestCase.php',
     'PhabricatorUser' => 'applications/people/storage/PhabricatorUser.php',
     'PhabricatorUserDAO' => 'applications/people/storage/PhabricatorUserDAO.php',
-    'PhabricatorUserEditor' => 'applications/people/PhabricatorUserEditor.php',
+    'PhabricatorUserEditor' => 'applications/people/editor/PhabricatorUserEditor.php',
     'PhabricatorUserEmail' => 'applications/people/storage/PhabricatorUserEmail.php',
     'PhabricatorUserLDAPInfo' => 'applications/people/storage/PhabricatorUserLDAPInfo.php',
     'PhabricatorUserLog' => 'applications/people/storage/PhabricatorUserLog.php',
@@ -1554,6 +1556,7 @@ phutil_register_library_map(array(
     'PhabricatorUserStatusInvalidEpochException' => 'applications/people/exception/PhabricatorUserStatusInvalidEpochException.php',
     'PhabricatorUserStatusOverlapException' => 'applications/people/exception/PhabricatorUserStatusOverlapException.php',
     'PhabricatorUserTestCase' => 'applications/people/storage/__tests__/PhabricatorUserTestCase.php',
+    'PhabricatorUserTransaction' => 'applications/people/storage/PhabricatorUserTransaction.php',
     'PhabricatorWorkboardExample' => 'applications/uiexample/examples/PhabricatorWorkboardExample.php',
     'PhabricatorWorkboardView' => 'view/layout/PhabricatorWorkboardView.php',
     'PhabricatorWorker' => 'infrastructure/daemon/workers/PhabricatorWorker.php',
@@ -2764,6 +2767,7 @@ phutil_register_library_map(array(
     'PhabricatorCustomFieldDataNotAvailableException' => 'Exception',
     'PhabricatorCustomFieldImplementationIncompleteException' => 'Exception',
     'PhabricatorCustomFieldIndexStorage' => 'PhabricatorLiskDAO',
+    'PhabricatorCustomFieldNotAttachedException' => 'Exception',
     'PhabricatorCustomFieldNumericIndexStorage' => 'PhabricatorCustomFieldIndexStorage',
     'PhabricatorCustomFieldStorage' => 'PhabricatorLiskDAO',
     'PhabricatorCustomFieldStringIndexStorage' => 'PhabricatorCustomFieldIndexStorage',
@@ -3385,6 +3389,7 @@ phutil_register_library_map(array(
     'PhabricatorUserStatusInvalidEpochException' => 'Exception',
     'PhabricatorUserStatusOverlapException' => 'Exception',
     'PhabricatorUserTestCase' => 'PhabricatorTestCase',
+    'PhabricatorUserTransaction' => 'PhabricatorApplicationTransaction',
     'PhabricatorWorkboardExample' => 'PhabricatorUIExample',
     'PhabricatorWorkboardView' => 'AphrontView',
     'PhabricatorWorkerActiveTask' => 'PhabricatorWorkerTask',
diff --git a/src/applications/people/PhabricatorUserEditor.php b/src/applications/people/editor/PhabricatorUserEditor.php
similarity index 100%
rename from src/applications/people/PhabricatorUserEditor.php
rename to src/applications/people/editor/PhabricatorUserEditor.php
diff --git a/src/applications/people/storage/PhabricatorUserTransaction.php b/src/applications/people/storage/PhabricatorUserTransaction.php
new file mode 100644
index 0000000000..67095c216d
--- /dev/null
+++ b/src/applications/people/storage/PhabricatorUserTransaction.php
@@ -0,0 +1,23 @@
+<?php
+
+final class PhabricatorUserTransaction
+  extends PhabricatorApplicationTransaction {
+
+  public function getApplicationName() {
+    return 'user';
+  }
+
+  public function getApplicationTransactionType() {
+    return PhabricatorPHIDConstants::PHID_TYPE_USER;
+  }
+
+  public function getApplicationTransactionCommentObject() {
+    return null;
+  }
+
+  public function getApplicationObjectTypeName() {
+    return pht('user');
+  }
+
+}
+
diff --git a/src/applications/transactions/constants/PhabricatorTransactions.php b/src/applications/transactions/constants/PhabricatorTransactions.php
index a71f0e556f..6ad787cfe9 100644
--- a/src/applications/transactions/constants/PhabricatorTransactions.php
+++ b/src/applications/transactions/constants/PhabricatorTransactions.php
@@ -7,6 +7,7 @@ final class PhabricatorTransactions {
   const TYPE_VIEW_POLICY  = 'core:view-policy';
   const TYPE_EDIT_POLICY  = 'core:edit-policy';
   const TYPE_EDGE         = 'core:edge';
+  const TYPE_CUSTOMFIELD  = 'core:customfield';
 
   const COLOR_RED         = 'red';
   const COLOR_ORANGE      = 'orange';
diff --git a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
index f427b62a04..e4308c833c 100644
--- a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
+++ b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
@@ -78,6 +78,10 @@ abstract class PhabricatorApplicationTransactionEditor
       $types[] = PhabricatorTransactions::TYPE_SUBSCRIBERS;
     }
 
+    if ($this->object instanceof PhabricatorCustomFieldInterface) {
+      $types[] = PhabricatorTransactions::TYPE_CUSTOMFIELD;
+    }
+
     return $types;
   }
 
@@ -121,6 +125,9 @@ abstract class PhabricatorApplicationTransactionEditor
           $old_edges = $old_edges[$edge_src][$edge_type];
         }
         return $old_edges;
+      case PhabricatorTransactions::TYPE_CUSTOMFIELD:
+        $field = $this->getCustomFieldForTransaction($object, $xaction);
+        return $field->getOldValueForApplicationTransactions();
       default:
         return $this->getCustomTransactionOldValue($object, $xaction);
     }
@@ -137,6 +144,9 @@ abstract class PhabricatorApplicationTransactionEditor
         return $xaction->getNewValue();
       case PhabricatorTransactions::TYPE_EDGE:
         return $this->getEdgeTransactionNewValue($xaction);
+      case PhabricatorTransactions::TYPE_CUSTOMFIELD:
+        $field = $this->getCustomFieldForTransaction($object, $xaction);
+        return $field->getNewValueForApplicationTransactions();
       default:
         return $this->getCustomTransactionNewValue($object, $xaction);
     }
@@ -161,6 +171,9 @@ abstract class PhabricatorApplicationTransactionEditor
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return $xaction->hasComment();
+      case PhabricatorTransactions::TYPE_CUSTOMFIELD:
+        $field = $this->getCustomFieldForTransaction($object, $xaction);
+        return $field->getApplicationTransactionHasEffect($xaction);
     }
 
     return ($xaction->getOldValue() !== $xaction->getNewValue());
@@ -176,6 +189,9 @@ abstract class PhabricatorApplicationTransactionEditor
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         $object->setEditPolicy($xaction->getNewValue());
         break;
+      case PhabricatorTransactions::TYPE_CUSTOMFIELD:
+        $field = $this->getCustomFieldForTransaction($object, $xaction);
+        return $field->applyApplicationTransactionInternalEffects($xaction);
     }
     return $this->applyCustomInternalTransaction($object, $xaction);
   }
@@ -240,6 +256,9 @@ abstract class PhabricatorApplicationTransactionEditor
 
         $editor->save();
         break;
+      case PhabricatorTransactions::TYPE_CUSTOMFIELD:
+        $field = $this->getCustomFieldForTransaction($object, $xaction);
+        return $field->applyApplicationTransactionExternalEffects($xaction);
     }
 
     return $this->applyCustomExternalTransaction($object, $xaction);
@@ -1244,4 +1263,41 @@ abstract class PhabricatorApplicationTransactionEditor
     return false;
   }
 
+
+/* -( Custom Fields  )------------------------------------------------------- */
+
+
+  /**
+   * @task customfield
+   */
+  private function getCustomFieldForTransaction(
+    PhabricatorLiskDAO $object,
+    PhabricatorApplicationTransaction $xaction) {
+
+    $field_key = $xaction->getMetadataValue('customfield:key');
+    if (!$field_key) {
+      throw new Exception(
+        "Custom field transaction has no 'customfield:key'!");
+    }
+
+    $field = PhabricatorCustomField::getObjectField(
+      $object,
+      PhabricatorCustomField::ROLE_APPLICATIONTRANSACTIONS,
+      $field_key);
+
+    if (!$field) {
+      throw new Exception(
+        "Custom field transaction has invalid 'customfield:key'; field ".
+        "'{$field_key}' is disabled or does not exist.");
+    }
+
+    if (!$field->shouldAppearInApplicationTransactions()) {
+      throw new Exception(
+        "Custom field transaction '{$field_key}' does not implement ".
+        "integration for ApplicationTransactions.");
+    }
+
+    return $field;
+  }
+
 }
diff --git a/src/infrastructure/customfield/exception/PhabricatorCustomFieldNotAttachedException.php b/src/infrastructure/customfield/exception/PhabricatorCustomFieldNotAttachedException.php
new file mode 100644
index 0000000000..a633b2c4de
--- /dev/null
+++ b/src/infrastructure/customfield/exception/PhabricatorCustomFieldNotAttachedException.php
@@ -0,0 +1,6 @@
+<?php
+
+final class PhabricatorCustomFieldNotAttachedException
+  extends Exception {
+
+}
diff --git a/src/infrastructure/customfield/field/PhabricatorCustomField.php b/src/infrastructure/customfield/field/PhabricatorCustomField.php
index 877f83ada2..8de6c90e54 100644
--- a/src/infrastructure/customfield/field/PhabricatorCustomField.php
+++ b/src/infrastructure/customfield/field/PhabricatorCustomField.php
@@ -1,35 +1,100 @@
 <?php
 
 /**
+ * @task apps       Building Applications with Custom Fields
+ * @task core       Core Properties and Field Identity
  * @task context    Contextual Data
  * @task storage    Field Storage
+ * @task appsearch  Integration with ApplicationSearch
+ * @task appxaction Integration with ApplicationTransactions
  */
 abstract class PhabricatorCustomField {
 
   private $viewer;
+  private $object;
 
-  abstract public function getFieldKey();
+  const ROLE_APPLICATIONTRANSACTIONS  = 'ApplicationTransactions';
+  const ROLE_APPLICAITONSEARCH        = 'ApplicationSearch';
+  const ROLE_STORAGE                  = 'storage';
+  const ROLE_DEFAULT                  = 'default';
 
-  public function getFieldIndex() {
-    return PhabricatorHash::digestForIndex($this->getFieldKey());
+
+/* -(  Building Applications with Custom Fields  )--------------------------- */
+
+
+  /**
+   * @task apps
+   */
+  public static function raiseUnattachedException(
+    PhabricatorCustomFieldInterface $object,
+    $role) {
+    throw new PhabricatorCustomFieldNotAttachedException(
+      "Call attachCustomFields() before getCustomFields()!");
   }
 
-  public function getFieldName() {
-    return $this->getFieldKey();
+
+  /**
+   * @task apps
+   */
+  public static function getObjectFields(
+    PhabricatorCustomFieldInterface $object,
+    $role) {
+
+    try {
+      $fields = $object->getCustomFields($role);
+    } catch (PhabricatorCustomFieldNotAttachedException $ex) {
+      $base_class = $object->getCustomFieldBaseClass();
+
+      if (!($base_class instanceof PhabricatorCustomField)) {
+        $obj_class = get_class($object);
+        throw new Exception(
+          "Object (of class '{$obj_class}') returned '{$base_class}' as its ".
+          "getCustomFieldBaseClass(), but this is not a recognized subclass ".
+          "of PhabricatorCustomField.");
+      }
+
+      $spec = $object->getCustomFieldSpecificationForRole($role);
+      if (!is_array($spec)) {
+        $obj_class = get_class($object);
+        throw new Exception(
+          "Expected an array from getCustomFieldSpecificationForRole() for ".
+          "object of class '{$obj_class}'.");
+      }
+
+      $fields = PhabricatorCustomField::buildFieldList($base_class, $spec);
+
+      foreach ($fields as $key => $field) {
+        if (!$field->shouldEnableForRole($role)) {
+          unset($fields[$key]);
+        }
+      }
+
+      foreach ($fields as $field) {
+        $field->setObject($object);
+      }
+
+      $object->attachCustomFields($role, $fields);
+    }
+
+    return $fields;
   }
 
-  public function createFields() {
-    return array($this);
+
+  /**
+   * @task apps
+   */
+  public static function getObjectField(
+    PhabricatorCustomFieldInterface $object,
+    $role,
+    $field_key) {
+
+    return idx(self::getObjectFields($object, $role), $field_key);
   }
 
-  public function isFieldEnabled() {
-    return true;
-  }
-
-  public function canDisableField() {
-    return true;
-  }
 
+  /**
+   * @task apps
+   */
   public static function buildFieldList($base_class, array $spec) {
     $this_class = __CLASS__;
     if (!($base_class instanceof $this_class)) {
@@ -81,9 +146,153 @@ abstract class PhabricatorCustomField {
   }
 
 
+/* -(  Core Properties and Field Identity  )--------------------------------- */
+
+
+  /**
+   * Return a key which uniquely identifies this field, like
+   * "mycompany.dinosaur.count". Normally you should provide some level of
+   * namespacing to prevent collisions.
+   *
+   * @return string String which uniquely identifies this field.
+   * @task core
+   */
+  abstract public function getFieldKey();
+
+
+  /**
+   * Return a human-readable field name.
+   *
+   * @return string Human readable field name.
+   * @task core
+   */
+  public function getFieldName() {
+    return $this->getFieldKey();
+  }
+
+
+  /**
+   * Return a short, human-readable description of the field's behavior. This
+   * provides more context to administrators when they are customizing fields.
+   *
+   * @return string|null Optional human-readable description.
+   * @task core
+   */
+  public function getFieldDescription() {
+    return null;
+  }
+
+
+  /**
+   * Most field implementations are unique, in that one class corresponds to
+   * one field. However, some field implementations are general and a single
+   * implementation may drive several fields.
+   *
+   * For general implementations, the general field implementation can return
+   * multiple field instances here.
+   *
+   * @return list<PhabricatorCustomField> List of fields.
+   * @task core
+   */
+  public function createFields() {
+    return array($this);
+  }
+
+
+  /**
+   * You can return `false` here if the field should not be enabled for any
+   * role. For example, it might depend on something (like an application or
+   * library) which isn't installed, or might have some global configuration
+   * which allows it to be disabled.
+   *
+   * @return bool False to completely disable this field for all roles.
+   * @task core
+   */
+  public function isFieldEnabled() {
+    return true;
+  }
+
+
+  /**
+   * Low level selector for field availability. Fields can appear in different
+   * roles (like an edit view, a list view, etc.), but not every field needs
+   * to appear everywhere. Fields that are disabled in a role won't appear in
+   * that context within applications.
+   *
+   * Normally, you do not need to override this method. Instead, override the
+   * methods specific to roles you want to enable. For example, implement
+   * @{method:getStorageKey()} to activate the `'storage'` role.
+   *
+   * @return bool True to enable the field for the given role.
+   * @task core
+   */
+  public function shouldEnableForRole($role) {
+    switch ($role) {
+      case self::ROLE_APPLICATIONTRANSACTIONS:
+        return $this->shouldAppearInApplicationTransactions();
+      case self::ROLE_APPLICATIONSEARCH:
+        return $this->shouldAppearInApplicationSearch();
+      case self::ROLE_STORAGE:
+        return ($this->getStorageKey() !== null);
+      case self::ROLE_DEFAULT:
+        return true;
+      default:
+        throw new Exception("Unknown field role '{$role}'!");
+    }
+  }
+
+
+  /**
+   * Allow administrators to disable this field. Most fields should allow this,
+   * but some are fundamental to the behavior of the application and can be
+   * locked down to avoid chaos, disorder, and the decline of civilization.
+   *
+   * @return bool False to prevent this field from being disabled through
+   *              configuration.
+   * @task core
+   */
+  public function canDisableField() {
+    return true;
+  }
+
+
+  /**
+   * Return an index string which uniquely identifies this field.
+   *
+   * @return string Index string which uniquely identifies this field.
+   * @task core
+   */
+  final public function getFieldIndex() {
+    return PhabricatorHash::digestForIndex($this->getFieldKey());
+  }
+
+
 /* -(  Contextual Data  )---------------------------------------------------- */
 
 
+  /**
+   * Sets the object this field belongs to.
+   *
+   * @param PhabricatorCustomFieldInterface The object this field belongs to.
+   * @task context
+   */
+  final public function setObject(PhabricatorCustomFieldInterface $object) {
+    $this->object = $object;
+    return $this;
+  }
+
+
+  /**
+   * Get the object this field belongs to.
+   *
+   * @return PhabricatorCustomFieldInterface The object this field belongs to.
+   * @task context
+   */
+  final public function getObject() {
+    return $this->object;
+  }
+
+
   /**
    * @task context
    */
@@ -143,6 +352,19 @@ abstract class PhabricatorCustomField {
   }
 
 
+  /**
+   * Return a new, empty storage object. This should be a subclass of
+   * @{class:PhabricatorCustomFieldStorage} which is bound to the application's
+   * database.
+   *
+   * @return PhabricatorCustomFieldStorage New empty storage object.
+   * @task storage
+   */
+  public function getStorageObject() {
+    throw new PhabricatorCustomFieldImplementationIncompleteException($this);
+  }
+
+
   /**
    * Return a serialized representation of the field value, appropriate for
    * storing in auxiliary field storage. You must implement this method if
@@ -277,4 +499,98 @@ abstract class PhabricatorCustomField {
       ->setIndexValue($value);
   }
 
+
+/* -(  ApplicationTransactions  )-------------------------------------------- */
+
+
+  /**
+   * Appearing in ApplicationTrasactions allows a field to be edited using
+   * standard workflows.
+   *
+   * @return bool True to appear in ApplicationTransactions.
+   * @task appxaction
+   */
+  public function shouldAppearInApplicationTransactions() {
+    return false;
+  }
+
+
+  /**
+   * @task appxaction
+   */
+  public function getOldValueForApplicationTransactions() {
+    return $this->getValueForStorage();
+  }
+
+
+  /**
+   * @task appxaction
+   */
+  public function setValueFromApplicationTransactions($value) {
+    return $this->setValueFromStorage($value);
+  }
+
+
+  /**
+   * @task appxaction
+   */
+  public function getNewValueForApplicationTransactions(
+    PhabricatorApplicationTransaction $xaction) {
+    return $xaction->getNewValue();
+  }
+
+
+  /**
+   * @task appxaction
+   */
+  public function getApplicationTransactionHasEffect(
+    PhabricatorApplicationTransaction $xaction) {
+    return ($xaction->getOldValue() !== $xaction->getNewValue());
+  }
+
+
+  /**
+   * @task appxaction
+   */
+  public function applyApplicationTransactionInternalEffects(
+    PhabricatorApplicationTransaction $xaction) {
+    return;
+  }
+
+
+  /**
+   * @task appxaction
+   */
+  public function applyApplicationTransactionExternalEffects(
+    PhabricatorApplicationTransaction $xaction) {
+    if (!$this->shouldEnableForRole(self::ROLE_STORAGE)) {
+      return;
+    }
+
+    $this->setValueFromApplicationTransaction($xaction->getNewValue());
+    $value = $this->getValueForStorage();
+
+    $table = $this->newStorageObject();
+    $conn_w = $table->establishConnection('w');
+
+    if ($value === null) {
+      queryfx(
+        $conn_w,
+        'DELETE FROM %T WHERE objectPHID = %s AND fieldIndex = %s',
+        $this->getObject()->getPHID(),
+        $this->getFieldIndex());
+    } else {
+      queryfx(
+        $conn_w,
+        'INSERT INTO %T (objectPHID, fieldIndex, fieldValue)
+          VALUES (%s, %s, %s)
+          ON DUPLICATE KEY UPDATE fieldValue = VALUES(fieldValue)',
+        $this->getObject()->getPHID(),
+        $this->getFieldIndex(),
+        $value);
+    }
+
+    return;
+  }
+
 }
diff --git a/src/infrastructure/customfield/interface/PhabricatorCustomFieldInterface.php b/src/infrastructure/customfield/interface/PhabricatorCustomFieldInterface.php
new file mode 100644
index 0000000000..1695f6468b
--- /dev/null
+++ b/src/infrastructure/customfield/interface/PhabricatorCustomFieldInterface.php
@@ -0,0 +1,41 @@
+<?php
+
+interface PhabricatorCustomFieldInterface {
+
+  public function getCustomFieldBaseClass();
+  public function getCustomFieldSpecificationForRole($role);
+  public function getCustomFields($role);
+  public function attachCustomFields($role, array $fields);
+
+}
+
+
+// TEMPLATE IMPLEMENTATION /////////////////////////////////////////////////////
+
+
+/* -(  PhabricatorCustomFieldInterface  )------------------------------------ */
+/*
+
+  private $customFields = array();
+
+  public function getCustomFieldSpecificationForRole($role) {
+    return PhabricatorEnv::getEnvConfig(<<<'application.fields'>>>);
+  }
+
+  public function getCustomFieldBaseClass() {
+    return <<<<'YourApplicationHereCustomField'>>>>;
+  }
+
+  public function getCustomFields($role) {
+    if (idx($this->customFields, $role) === null) {
+      PhabricatorCustomField::raiseUnattachedException($this, $role);
+    }
+    return $this->customFields;
+  }
+
+  public function attachCustomFields($role, array $fields) {
+    $this->customFields[$role] = $fields;
+    return $this;
+  }
+
+*/