diff --git a/synapse/appservice/__init__.py b/synapse/appservice/__init__.py
index b1b91d0a5..bde9b51b2 100644
--- a/synapse/appservice/__init__.py
+++ b/synapse/appservice/__init__.py
@@ -81,13 +81,17 @@ class ApplicationService(object):
     NS_LIST = [NS_USERS, NS_ALIASES, NS_ROOMS]
 
     def __init__(self, token, url=None, namespaces=None, hs_token=None,
-                 sender=None, id=None):
+                 sender=None, id=None, protocols=None):
         self.token = token
         self.url = url
         self.hs_token = hs_token
         self.sender = sender
         self.namespaces = self._check_namespaces(namespaces)
         self.id = id
+        if protocols:
+            self.protocols = set(protocols)
+        else:
+            self.protocols = set()
 
     def _check_namespaces(self, namespaces):
         # Sanity check that it is of the form:
@@ -219,6 +223,9 @@ class ApplicationService(object):
             or user_id == self.sender
         )
 
+    def is_interested_in_protocol(self, protocol):
+        return protocol in self.protocols
+
     def is_exclusive_alias(self, alias):
         return self._is_exclusive(ApplicationService.NS_ALIASES, alias)
 
diff --git a/synapse/appservice/api.py b/synapse/appservice/api.py
index 6da6a1b62..066127b66 100644
--- a/synapse/appservice/api.py
+++ b/synapse/appservice/api.py
@@ -17,6 +17,7 @@ from twisted.internet import defer
 from synapse.api.errors import CodeMessageException
 from synapse.http.client import SimpleHttpClient
 from synapse.events.utils import serialize_event
+from synapse.types import ThirdPartyEntityKind
 
 import logging
 import urllib
@@ -24,6 +25,28 @@ import urllib
 logger = logging.getLogger(__name__)
 
 
+def _is_valid_3pe_result(r, field):
+    if not isinstance(r, dict):
+        return False
+
+    for k in (field, "protocol"):
+        if k not in r:
+            return False
+        if not isinstance(r[k], str):
+            return False
+
+    if "fields" not in r:
+        return False
+    fields = r["fields"]
+    if not isinstance(fields, dict):
+        return False
+    for k in fields.keys():
+        if not isinstance(fields[k], str):
+            return False
+
+    return True
+
+
 class ApplicationServiceApi(SimpleHttpClient):
     """This class manages HS -> AS communications, including querying and
     pushing.
@@ -71,6 +94,43 @@ class ApplicationServiceApi(SimpleHttpClient):
             logger.warning("query_alias to %s threw exception %s", uri, ex)
         defer.returnValue(False)
 
+    @defer.inlineCallbacks
+    def query_3pe(self, service, kind, protocol, fields):
+        if kind == ThirdPartyEntityKind.USER:
+            uri = "%s/3pu/%s" % (service.url, urllib.quote(protocol))
+            required_field = "userid"
+        elif kind == ThirdPartyEntityKind.LOCATION:
+            uri = "%s/3pl/%s" % (service.url, urllib.quote(protocol))
+            required_field = "alias"
+        else:
+            raise ValueError(
+                "Unrecognised 'kind' argument %r to query_3pe()", kind
+            )
+
+        try:
+            response = yield self.get_json(uri, fields)
+            if not isinstance(response, list):
+                logger.warning(
+                    "query_3pe to %s returned an invalid response %r",
+                    uri, response
+                )
+                defer.returnValue([])
+
+            ret = []
+            for r in response:
+                if _is_valid_3pe_result(r, field=required_field):
+                    ret.append(r)
+                else:
+                    logger.warning(
+                        "query_3pe to %s returned an invalid result %r",
+                        uri, r
+                    )
+
+            defer.returnValue(ret)
+        except Exception as ex:
+            logger.warning("query_3pe to %s threw exception %s", uri, ex)
+            defer.returnValue([])
+
     @defer.inlineCallbacks
     def push_bulk(self, service, events, txn_id=None):
         events = self._serialize(events)
diff --git a/synapse/config/appservice.py b/synapse/config/appservice.py
index 70d28892c..dfe43b0b4 100644
--- a/synapse/config/appservice.py
+++ b/synapse/config/appservice.py
@@ -123,6 +123,15 @@ def _load_appservice(hostname, as_info, config_filename):
                     raise ValueError(
                         "Missing/bad type 'exclusive' key in %s", regex_obj
                     )
+    # protocols check
+    protocols = as_info.get("protocols")
+    if protocols:
+        # Because strings are lists in python
+        if isinstance(protocols, str) or not isinstance(protocols, list):
+            raise KeyError("Optional 'protocols' must be a list if present.")
+        for p in protocols:
+            if not isinstance(p, str):
+                raise KeyError("Bad value for 'protocols' item")
     return ApplicationService(
         token=as_info["as_token"],
         url=as_info["url"],
@@ -130,4 +139,5 @@ def _load_appservice(hostname, as_info, config_filename):
         hs_token=as_info["hs_token"],
         sender=user_id,
         id=as_info["id"],
+        protocols=protocols,
     )
diff --git a/synapse/handlers/appservice.py b/synapse/handlers/appservice.py
index 6556dd1ae..dd285452c 100644
--- a/synapse/handlers/appservice.py
+++ b/synapse/handlers/appservice.py
@@ -159,6 +159,22 @@ class ApplicationServicesHandler(object):
                 )
                 defer.returnValue(result)
 
+    @defer.inlineCallbacks
+    def query_3pe(self, kind, protocol, fields):
+        services = yield self._get_services_for_3pn(protocol)
+
+        results = yield defer.DeferredList([
+            self.appservice_api.query_3pe(service, kind, protocol, fields)
+            for service in services
+        ], consumeErrors=True)
+
+        ret = []
+        for (success, result) in results:
+            if success:
+                ret.extend(result)
+
+        defer.returnValue(ret)
+
     @defer.inlineCallbacks
     def _get_services_for_event(self, event):
         """Retrieve a list of application services interested in this event.
@@ -187,6 +203,14 @@ class ApplicationServicesHandler(object):
         ]
         defer.returnValue(interested_list)
 
+    @defer.inlineCallbacks
+    def _get_services_for_3pn(self, protocol):
+        services = yield self.store.get_app_services()
+        interested_list = [
+            s for s in services if s.is_interested_in_protocol(protocol)
+        ]
+        defer.returnValue(interested_list)
+
     @defer.inlineCallbacks
     def _is_unknown_user(self, user_id):
         if not self.is_mine_id(user_id):
diff --git a/synapse/rest/__init__.py b/synapse/rest/__init__.py
index 14227f1cd..2e0e6babe 100644
--- a/synapse/rest/__init__.py
+++ b/synapse/rest/__init__.py
@@ -47,6 +47,7 @@ from synapse.rest.client.v2_alpha import (
     report_event,
     openid,
     devices,
+    thirdparty,
 )
 
 from synapse.http.server import JsonResource
@@ -92,3 +93,4 @@ class ClientRestResource(JsonResource):
         report_event.register_servlets(hs, client_resource)
         openid.register_servlets(hs, client_resource)
         devices.register_servlets(hs, client_resource)
+        thirdparty.register_servlets(hs, client_resource)
diff --git a/synapse/rest/client/v2_alpha/thirdparty.py b/synapse/rest/client/v2_alpha/thirdparty.py
new file mode 100644
index 000000000..9abca3a8a
--- /dev/null
+++ b/synapse/rest/client/v2_alpha/thirdparty.py
@@ -0,0 +1,78 @@
+# -*- coding: utf-8 -*-
+# Copyright 2015, 2016 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import logging
+
+from twisted.internet import defer
+
+from synapse.http.servlet import RestServlet
+from synapse.types import ThirdPartyEntityKind
+from ._base import client_v2_patterns
+
+logger = logging.getLogger(__name__)
+
+
+class ThirdPartyUserServlet(RestServlet):
+    PATTERNS = client_v2_patterns("/3pu(/(?P<protocol>[^/]+))?$",
+                                  releases=())
+
+    def __init__(self, hs):
+        super(ThirdPartyUserServlet, self).__init__()
+
+        self.auth = hs.get_auth()
+        self.appservice_handler = hs.get_application_service_handler()
+
+    @defer.inlineCallbacks
+    def on_GET(self, request, protocol):
+        yield self.auth.get_user_by_req(request)
+
+        fields = request.args
+        del fields["access_token"]
+
+        results = yield self.appservice_handler.query_3pe(
+            ThirdPartyEntityKind.USER, protocol, fields
+        )
+
+        defer.returnValue((200, results))
+
+
+class ThirdPartyLocationServlet(RestServlet):
+    PATTERNS = client_v2_patterns("/3pl(/(?P<protocol>[^/]+))?$",
+                                  releases=())
+
+    def __init__(self, hs):
+        super(ThirdPartyLocationServlet, self).__init__()
+
+        self.auth = hs.get_auth()
+        self.appservice_handler = hs.get_application_service_handler()
+
+    @defer.inlineCallbacks
+    def on_GET(self, request, protocol):
+        yield self.auth.get_user_by_req(request)
+
+        fields = request.args
+        del fields["access_token"]
+
+        results = yield self.appservice_handler.query_3pe(
+            ThirdPartyEntityKind.LOCATION, protocol, fields
+        )
+
+        defer.returnValue((200, results))
+
+
+def register_servlets(hs, http_server):
+    ThirdPartyUserServlet(hs).register(http_server)
+    ThirdPartyLocationServlet(hs).register(http_server)
diff --git a/synapse/types.py b/synapse/types.py
index 5349b0c45..fd17ecbbe 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -269,3 +269,10 @@ class RoomStreamToken(namedtuple("_StreamToken", "topological stream")):
             return "t%d-%d" % (self.topological, self.stream)
         else:
             return "s%d" % (self.stream,)
+
+
+# Some arbitrary constants used for internal API enumerations. Don't rely on
+# exact values; always pass or compare symbolically
+class ThirdPartyEntityKind(object):
+    USER = 'user'
+    LOCATION = 'location'