diff --git a/internal_packages/category-picker/lib/category-picker.cjsx b/internal_packages/category-picker/lib/category-picker.cjsx
index 6314368d2..9b6b8aca4 100644
--- a/internal_packages/category-picker/lib/category-picker.cjsx
+++ b/internal_packages/category-picker/lib/category-picker.cjsx
@@ -301,7 +301,7 @@ class CategoryPicker extends React.Component
 
   _categoryUsageCount: (props, categories) =>
     categoryUsageCount = {}
-    _.flatten(@_threads(props).map(@_threadCategories)).forEach (category) ->
+    _.flatten(_.pluck(@_threads(props), 'categories')).forEach (category) ->
       categoryUsageCount[category.id] ?= 0
       categoryUsageCount[category.id] += 1
     return categoryUsageCount
@@ -339,13 +339,6 @@ class CategoryPicker extends React.Component
     item.numThreads = numThreads
     item
 
-  _threadCategories: (thread) =>
-    if @_account.usesLabels()
-      return (thread.labels ? [])
-    else if @_account.usesFolders()
-      return (thread.folders ? [])
-    else throw new Error("Invalid organizationUnit")
-
   _threads: (props = @props) =>
     if props.items then return (props.items ? [])
     else if props.thread then return [props.thread]
diff --git a/internal_packages/message-list/lib/message-list.cjsx b/internal_packages/message-list/lib/message-list.cjsx
index b12254637..72aa02b1f 100755
--- a/internal_packages/message-list/lib/message-list.cjsx
+++ b/internal_packages/message-list/lib/message-list.cjsx
@@ -8,6 +8,7 @@ MessageItemContainer = require './message-item-container'
  Message,
  DraftStore,
  MessageStore,
+ AccountStore,
  DatabaseStore,
  WorkspaceStore,
  ChangeLabelsTask,
@@ -244,6 +245,8 @@ class MessageList extends React.Component
       </div>
 
   _renderLabels: =>
+    account = AccountStore.accountForId(@state.currentThread.accountId)
+    return false unless account.usesLabels()
     labels = @state.currentThread.sortedCategories()
     labels = _.reject labels, (l) -> l.name is 'important'
     labels.map (label) =>
diff --git a/src/components/mail-important-icon.cjsx b/src/components/mail-important-icon.cjsx
index ab506bfa6..1865ab1f8 100644
--- a/src/components/mail-important-icon.cjsx
+++ b/src/components/mail-important-icon.cjsx
@@ -53,7 +53,7 @@ class MailImportantIcon extends React.Component
   render: =>
     return false unless @state.visible
 
-    isImportant = @state.categoryId and _.findWhere(@props.thread.labels, {id: @state.categoryId})?
+    isImportant = @state.categoryId and _.findWhere(@props.thread.categories, {id: @state.categoryId})?
 
     classes = classNames
       'mail-important-icon': true
diff --git a/src/flux/attributes/attribute-collection.coffee b/src/flux/attributes/attribute-collection.coffee
index c8dc99144..a09e98754 100644
--- a/src/flux/attributes/attribute-collection.coffee
+++ b/src/flux/attributes/attribute-collection.coffee
@@ -15,7 +15,7 @@ join table associating the ID of the model with the IDs of models in the collect
 Collection attributes have an additional clause builder, `contains`:
 
 ```coffee
-DatabaseStore.findAll(Thread).where([Thread.attributes.labels.contains('inbox')])
+DatabaseStore.findAll(Thread).where([Thread.attributes.categories.contains('inbox')])
 ```
 
 This is equivalent to writing the following SQL:
diff --git a/src/flux/models/query.coffee b/src/flux/models/query.coffee
index f46d07b6b..fe37035c2 100644
--- a/src/flux/models/query.coffee
+++ b/src/flux/models/query.coffee
@@ -25,7 +25,7 @@ query.then (thread) ->
 
 ```coffee
 query = DatabaseStore.findAll(Thread)
-query.where([Thread.attributes.labels.contains('label-id')])
+query.where([Thread.attributes.categories.contains('label-id')])
      .order([Thread.attributes.lastMessageReceivedTimestamp.descending()])
      .limit(100).offset(50)
      .then (threads) ->
diff --git a/src/flux/stores/database-setup-query-builder.coffee b/src/flux/stores/database-setup-query-builder.coffee
index b619e27cd..b673bf1e2 100644
--- a/src/flux/stores/database-setup-query-builder.coffee
+++ b/src/flux/stores/database-setup-query-builder.coffee
@@ -35,7 +35,7 @@ class DatabaseSetupQueryBuilder
 
     # Identify collection attributes that can be matched against. These require
     # JOIN tables. (Right now the only one of these is Thread.folders or
-    # Thread.labels)
+    # Thread.categories)
     collectionAttributes = _.filter attributes, (attr) ->
       attr.queryable && attr instanceof AttributeCollection
     collectionAttributes.forEach (attribute) ->