diff --git a/api/users_servicer.py b/api/users_servicer.py
new file mode 100644
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--- /dev/null
+++ b/api/users_servicer.py
@@ -0,0 +1,217 @@
+# Copyright 2018 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+from __future__ import print_function
+from __future__ import division
+from __future__ import absolute_import
+
+from api import converters
+from api import monorail_servicer
+from api import converters
+from api.api_proto import users_pb2
+from api.api_proto import users_prpc_pb2
+from api.api_proto import user_objects_pb2
+from businesslogic import work_env
+from framework import authdata
+from framework import framework_views
+from framework import permissions
+
+class UsersServicer(monorail_servicer.MonorailServicer):
+  """Handle API requests related to User objects.
+
+  Each API request is implemented with a method as defined in the
+  .proto file that does any request-specific validation, uses work_env
+  to safely operate on business objects, and returns a response proto.
+  """
+
+  DESCRIPTION = users_prpc_pb2.UsersServiceDescription
+
+  @monorail_servicer.PRPCMethod
+  def GetUser(self, mc, request):
+    """Return info about the specified user."""
+    with work_env.WorkEnv(mc, self.services) as we:
+      users, linked_user_ids = we.ListReferencedUsers(
+          [request.user_ref.display_name])
+      linked_user_views = framework_views.MakeAllUserViews(
+          mc.cnxn, self.services.user, linked_user_ids)
+
+    with mc.profiler.Phase('converting to response objects'):
+      response_users = converters.ConvertUsers(users, linked_user_views)
+
+    return response_users[0]
+
+  @monorail_servicer.PRPCMethod
+  def ListReferencedUsers(self, mc, request):
+    """Return the list of existing users in a response proto."""
+    emails = request.emails
+    if request.user_refs:
+      emails = [user_ref.display_name for user_ref in request.user_refs]
+    with work_env.WorkEnv(mc, self.services) as we:
+      users, linked_user_ids = we.ListReferencedUsers(emails)
+      linked_user_views = framework_views.MakeAllUserViews(
+          mc.cnxn, self.services.user, linked_user_ids)
+
+    with mc.profiler.Phase('converting to response objects'):
+      response_users = converters.ConvertUsers(users, linked_user_views)
+      response = users_pb2.ListReferencedUsersResponse(users=response_users)
+
+    return response
+
+  @monorail_servicer.PRPCMethod
+  def GetMemberships(self, mc, request):
+    """Return the user groups for the given user visible to the requester."""
+    user_id = converters.IngestUserRef(
+        mc.cnxn, request.user_ref, self.services.user)
+
+    with work_env.WorkEnv(mc, self.services) as we:
+      group_ids = we.GetMemberships(user_id)
+
+    with mc.profiler.Phase('converting to response objects'):
+      groups_by_id = framework_views.MakeAllUserViews(
+          mc.cnxn, self.services.user, group_ids)
+      group_refs = converters.ConvertUserRefs(
+          group_ids, [], groups_by_id, True)
+
+      return users_pb2.GetMembershipsResponse(group_refs=group_refs)
+
+  @monorail_servicer.PRPCMethod
+  def GetUserStarCount(self, mc, request):
+    """Return the star count for a given user."""
+    user_id = converters.IngestUserRef(
+        mc.cnxn, request.user_ref, self.services.user)
+
+    with work_env.WorkEnv(mc, self.services) as we:
+      star_count = we.GetUserStarCount(user_id)
+
+    result = users_pb2.GetUserStarCountResponse(star_count=star_count)
+    return result
+
+  @monorail_servicer.PRPCMethod
+  def StarUser(self, mc, request):
+    """Star a given user."""
+    user_id = converters.IngestUserRef(
+        mc.cnxn, request.user_ref, self.services.user)
+
+    with work_env.WorkEnv(mc, self.services) as we:
+      we.StarUser(user_id, request.starred)
+      star_count = we.GetUserStarCount(user_id)
+
+    result = users_pb2.StarUserResponse(star_count=star_count)
+    return result
+
+  @monorail_servicer.PRPCMethod
+  def SetExpandPermsPreference(self, mc, request):
+    """Set a users preference on whether to expand perms by default."""
+    with work_env.WorkEnv(mc, self.services) as we:
+      we.UpdateUserSettings(
+          mc.auth.user_pb, keep_people_perms_open=request.expand_perms)
+
+    result = users_pb2.SetExpandPermsPreferenceResponse()
+    return result
+
+  def _SignedInOrSpecifiedUser(self, mc, request):
+    """If request specifies a user, return it.  Otherwise signed-in user."""
+    user_id = mc.auth.user_id
+    if request.HasField('user_ref'):
+      user_id = converters.IngestUserRef(
+          mc.cnxn, request.user_ref, self.services.user)
+    return user_id
+
+  @monorail_servicer.PRPCMethod
+  def GetSavedQueries(self, mc, request):
+    """Get a user's saved queries."""
+    user_id = self._SignedInOrSpecifiedUser(mc, request)
+
+    # Only site admins can view other user's saved queries.
+    if user_id != mc.auth.user_id and not mc.auth.user_pb.is_site_admin:
+      raise permissions.PermissionException(
+        'You are not allowed to view this user\'s saved queries')
+
+    saved_queries = self.services.features.GetSavedQueriesByUserID(
+        mc.cnxn, user_id)
+    return users_pb2.GetSavedQueriesResponse(
+        saved_queries=converters.IngestSavedQueries(mc.cnxn,
+            self.services.project, saved_queries))
+
+  @monorail_servicer.PRPCMethod
+  def GetUserPrefs(self, mc, request):
+    """Get a user's preferences."""
+    with work_env.WorkEnv(mc, self.services) as we:
+      userprefs = we.GetUserPrefs(self._SignedInOrSpecifiedUser(mc, request))
+
+    result = users_pb2.GetUserPrefsResponse(
+        prefs=converters.ConvertPrefValues(userprefs.prefs))
+    return result
+
+  @monorail_servicer.PRPCMethod
+  def SetUserPrefs(self, mc, request):
+    """Add to or set a users preferences."""
+    with work_env.WorkEnv(mc, self.services) as we:
+      pref_values = converters.IngestPrefValues(request.prefs)
+      we.SetUserPrefs(self._SignedInOrSpecifiedUser(mc, request), pref_values)
+
+    result = users_pb2.SetUserPrefsResponse()
+    return result
+
+  @monorail_servicer.PRPCMethod
+  def InviteLinkedParent(self, mc, request):
+    """Create a linked account invite."""
+    with work_env.WorkEnv(mc, self.services) as we:
+      we.InviteLinkedParent(request.email)
+
+    result = users_pb2.InviteLinkedParentResponse()
+    return result
+
+  @monorail_servicer.PRPCMethod
+  def AcceptLinkedChild(self, mc, request):
+    """Link a child account that has invited this account as parent."""
+    child_id = self.services.user.LookupUserID(mc.cnxn, request.email)
+    with work_env.WorkEnv(mc, self.services) as we:
+      we.AcceptLinkedChild(child_id)
+
+    result = users_pb2.AcceptLinkedChildResponse()
+    return result
+
+  @monorail_servicer.PRPCMethod
+  def UnlinkAccounts(self, mc, request):
+    """Unlink a specificed parent and child account."""
+    parent_id, child_id = converters.IngestUserRefs(
+        mc.cnxn, [request.parent, request.child], self.services.user)
+    with work_env.WorkEnv(mc, self.services) as we:
+      we.UnlinkAccounts(parent_id, child_id)
+
+    result = users_pb2.UnlinkAccountsResponse()
+    return result
+
+  @monorail_servicer.PRPCMethod
+  def GetUsersProjects(self, mc, request):
+    user_ids = converters.IngestUserRefs(
+        mc.cnxn, request.user_refs, self.services.user)
+    user_auths = [
+        authdata.AuthData.FromUserID(mc.cnxn, user_id, self.services)
+        for user_id in user_ids]
+
+    result = users_pb2.GetUsersProjectsResponse()
+    with work_env.WorkEnv(mc, self.services) as we:
+      for user_ref, auth in zip(request.user_refs, user_auths):
+        starred = we.ListStarredProjects(auth.user_id)
+        owner, _archived, member, contrib = we.GetUserProjects(
+            auth.effective_ids)
+        user_projects = result.users_projects.add()
+        user_projects.user_ref.CopyFrom(user_ref)
+        user_projects.owner_of.extend(p.project_name for p in owner)
+        user_projects.member_of.extend(p.project_name for p in member)
+        user_projects.contributor_to.extend(p.project_name for p in contrib)
+        user_projects.starred_projects.extend(p.project_name for p in starred)
+
+    return result
+
+  @monorail_servicer.PRPCMethod
+  def ExpungeUser(self, mc, request):
+    with work_env.WorkEnv(mc, self.services) as we:
+      we.ExpungeUsers([request.email])
+
+    response = users_pb2.ExpungeUserResponse()
+    return response