diff --git a/homeassistant/components/automation/__init__.py b/homeassistant/components/automation/__init__.py
index bc3c17e41da..8c490754f40 100644
--- a/homeassistant/components/automation/__init__.py
+++ b/homeassistant/components/automation/__init__.py
@@ -338,10 +338,9 @@ class AutomationEntity(ToggleEntity):
             yield from self.async_update_ha_state()
 
     @asyncio.coroutine
-    def async_remove(self):
-        """Remove automation from HASS."""
+    def async_will_remove_from_hass(self):
+        """Remove listeners when removing automation from HASS."""
         yield from self.async_turn_off()
-        yield from super().async_remove()
 
     @asyncio.coroutine
     def async_enable(self):
diff --git a/homeassistant/components/binary_sensor/flic.py b/homeassistant/components/binary_sensor/flic.py
index 51fffae5cc0..170f1818a0e 100644
--- a/homeassistant/components/binary_sensor/flic.py
+++ b/homeassistant/components/binary_sensor/flic.py
@@ -238,6 +238,5 @@ class FlicButton(BinarySensorDevice):
         import pyflic
 
         if connection_status == pyflic.ConnectionStatus.Disconnected:
-            _LOGGER.info("Button (%s) disconnected. Reason: %s",
-                         self.address, disconnect_reason)
-            self.remove()
+            _LOGGER.warning("Button (%s) disconnected. Reason: %s",
+                            self.address, disconnect_reason)
diff --git a/homeassistant/components/camera/__init__.py b/homeassistant/components/camera/__init__.py
index 6839c2c3b9c..1bb88050b2f 100644
--- a/homeassistant/components/camera/__init__.py
+++ b/homeassistant/components/camera/__init__.py
@@ -124,15 +124,15 @@ def async_setup(hass, config):
     """Set up the camera component."""
     component = EntityComponent(_LOGGER, DOMAIN, hass, SCAN_INTERVAL)
 
-    hass.http.register_view(CameraImageView(component.entities))
-    hass.http.register_view(CameraMjpegStream(component.entities))
+    hass.http.register_view(CameraImageView(component))
+    hass.http.register_view(CameraMjpegStream(component))
 
     yield from component.async_setup(config)
 
     @callback
     def update_tokens(time):
         """Update tokens of the entities."""
-        for entity in component.entities.values():
+        for entity in component.entities:
             entity.async_update_token()
             hass.async_add_job(entity.async_update_ha_state())
 
@@ -358,14 +358,14 @@ class CameraView(HomeAssistantView):
 
     requires_auth = False
 
-    def __init__(self, entities):
+    def __init__(self, component):
         """Initialize a basic camera view."""
-        self.entities = entities
+        self.component = component
 
     @asyncio.coroutine
     def get(self, request, entity_id):
         """Start a GET request."""
-        camera = self.entities.get(entity_id)
+        camera = self.component.get_entity(entity_id)
 
         if camera is None:
             status = 404 if request[KEY_AUTHENTICATED] else 401
diff --git a/homeassistant/components/group/__init__.py b/homeassistant/components/group/__init__.py
index 8b1e05e3122..a8529f18b69 100644
--- a/homeassistant/components/group/__init__.py
+++ b/homeassistant/components/group/__init__.py
@@ -42,8 +42,6 @@ ATTR_ORDER = 'order'
 ATTR_VIEW = 'view'
 ATTR_VISIBLE = 'visible'
 
-DATA_ALL_GROUPS = 'data_all_groups'
-
 SERVICE_SET_VISIBILITY = 'set_visibility'
 SERVICE_SET = 'set'
 SERVICE_REMOVE = 'remove'
@@ -250,8 +248,10 @@ def get_entity_ids(hass, entity_id, domain_filter=None):
 @asyncio.coroutine
 def async_setup(hass, config):
     """Set up all groups found definded in the configuration."""
-    component = EntityComponent(_LOGGER, DOMAIN, hass)
-    hass.data[DATA_ALL_GROUPS] = {}
+    component = hass.data.get(DOMAIN)
+
+    if component is None:
+        component = hass.data[DOMAIN] = EntityComponent(_LOGGER, DOMAIN, hass)
 
     yield from _async_process_config(hass, config, component)
 
@@ -271,10 +271,11 @@ def async_setup(hass, config):
     def groups_service_handler(service):
         """Handle dynamic group service functions."""
         object_id = service.data[ATTR_OBJECT_ID]
-        service_groups = hass.data[DATA_ALL_GROUPS]
+        entity_id = ENTITY_ID_FORMAT.format(object_id)
+        group = component.get_entity(entity_id)
 
         # new group
-        if service.service == SERVICE_SET and object_id not in service_groups:
+        if service.service == SERVICE_SET and group is None:
             entity_ids = service.data.get(ATTR_ENTITIES) or \
                 service.data.get(ATTR_ADD_ENTITIES) or None
 
@@ -289,12 +290,15 @@ def async_setup(hass, config):
                 user_defined=False,
                 **extra_arg
             )
+            return
 
+        if group is None:
+            _LOGGER.warning("%s:Group '%s' doesn't exist!",
+                            service.service, object_id)
             return
 
         # update group
         if service.service == SERVICE_SET:
-            group = service_groups[object_id]
             need_update = False
 
             if ATTR_ADD_ENTITIES in service.data:
@@ -333,12 +337,7 @@ def async_setup(hass, config):
 
         # remove group
         if service.service == SERVICE_REMOVE:
-            if object_id not in service_groups:
-                _LOGGER.warning("Group '%s' doesn't exist!", object_id)
-                return
-
-            del_group = service_groups.pop(object_id)
-            yield from del_group.async_stop()
+            yield from component.async_remove_entity(entity_id)
 
     hass.services.async_register(
         DOMAIN, SERVICE_SET, groups_service_handler,
@@ -395,7 +394,7 @@ class Group(Entity):
     """Track a group of entity ids."""
 
     def __init__(self, hass, name, order=None, visible=True, icon=None,
-                 view=False, control=None, user_defined=True):
+                 view=False, control=None, user_defined=True, entity_ids=None):
         """Initialize a group.
 
         This Object has factory function for creation.
@@ -405,7 +404,10 @@ class Group(Entity):
         self._state = STATE_UNKNOWN
         self._icon = icon
         self.view = view
-        self.tracking = []
+        if entity_ids:
+            self.tracking = tuple(ent_id.lower() for ent_id in entity_ids)
+        else:
+            self.tracking = tuple()
         self.group_on = None
         self.group_off = None
         self.visible = visible
@@ -439,23 +441,21 @@ class Group(Entity):
             hass, name,
             order=len(hass.states.async_entity_ids(DOMAIN)),
             visible=visible, icon=icon, view=view, control=control,
-            user_defined=user_defined
+            user_defined=user_defined, entity_ids=entity_ids
         )
 
         group.entity_id = async_generate_entity_id(
             ENTITY_ID_FORMAT, object_id or name, hass=hass)
 
-        # run other async stuff
-        if entity_ids is not None:
-            yield from group.async_update_tracked_entity_ids(entity_ids)
-        else:
-            yield from group.async_update_ha_state(True)
-
         # If called before the platform async_setup is called (test cases)
-        if DATA_ALL_GROUPS not in hass.data:
-            hass.data[DATA_ALL_GROUPS] = {}
+        component = hass.data.get(DOMAIN)
+
+        if component is None:
+            component = hass.data[DOMAIN] = \
+                EntityComponent(_LOGGER, DOMAIN, hass)
+
+        yield from component.async_add_entities([group], True)
 
-        hass.data[DATA_ALL_GROUPS][object_id] = group
         return group
 
     @property
@@ -534,10 +534,6 @@ class Group(Entity):
         yield from self.async_update_ha_state(True)
         self.async_start()
 
-    def start(self):
-        """Start tracking members."""
-        self.hass.add_job(self.async_start)
-
     @callback
     def async_start(self):
         """Start tracking members.
@@ -549,17 +545,15 @@ class Group(Entity):
                 self.hass, self.tracking, self._async_state_changed_listener
             )
 
-    def stop(self):
-        """Unregister the group from Home Assistant."""
-        run_coroutine_threadsafe(self.async_stop(), self.hass.loop).result()
-
     @asyncio.coroutine
     def async_stop(self):
         """Unregister the group from Home Assistant.
 
         This method must be run in the event loop.
         """
-        yield from self.async_remove()
+        if self._async_unsub_state_changed:
+            self._async_unsub_state_changed()
+            self._async_unsub_state_changed = None
 
     @asyncio.coroutine
     def async_update(self):
@@ -567,17 +561,19 @@ class Group(Entity):
         self._state = STATE_UNKNOWN
         self._async_update_group_state()
 
-    def async_remove(self):
-        """Remove group from HASS.
+    @asyncio.coroutine
+    def async_added_to_hass(self):
+        """Callback when added to HASS."""
+        if self.tracking:
+            self.async_start()
 
-        This method must be run in the event loop and returns a coroutine.
-        """
+    @asyncio.coroutine
+    def async_will_remove_from_hass(self):
+        """Callback when removed from HASS."""
         if self._async_unsub_state_changed:
             self._async_unsub_state_changed()
             self._async_unsub_state_changed = None
 
-        return super().async_remove()
-
     @asyncio.coroutine
     def _async_state_changed_listener(self, entity_id, old_state, new_state):
         """Respond to a member state changing.
diff --git a/homeassistant/components/mailbox/__init__.py b/homeassistant/components/mailbox/__init__.py
index 4f999649a44..a1e68555649 100644
--- a/homeassistant/components/mailbox/__init__.py
+++ b/homeassistant/components/mailbox/__init__.py
@@ -82,7 +82,7 @@ def async_setup(hass, config):
         mailbox_entity = MailboxEntity(hass, mailbox)
         component = EntityComponent(
             logging.getLogger(__name__), DOMAIN, hass, SCAN_INTERVAL)
-        yield from component.async_add_entity(mailbox_entity)
+        yield from component.async_add_entities([mailbox_entity])
 
     setup_tasks = [async_setup_platform(p_type, p_config) for p_type, p_config
                    in config_per_platform(config, DOMAIN)]
diff --git a/homeassistant/components/media_player/__init__.py b/homeassistant/components/media_player/__init__.py
index 44e6810fd5d..91bcb4d8af0 100644
--- a/homeassistant/components/media_player/__init__.py
+++ b/homeassistant/components/media_player/__init__.py
@@ -366,7 +366,7 @@ def async_setup(hass, config):
     component = EntityComponent(
         logging.getLogger(__name__), DOMAIN, hass, SCAN_INTERVAL)
 
-    hass.http.register_view(MediaPlayerImageView(component.entities))
+    hass.http.register_view(MediaPlayerImageView(component))
 
     yield from component.async_setup(config)
 
@@ -929,14 +929,14 @@ class MediaPlayerImageView(HomeAssistantView):
     url = '/api/media_player_proxy/{entity_id}'
     name = 'api:media_player:image'
 
-    def __init__(self, entities):
+    def __init__(self, component):
         """Initialize a media player view."""
-        self.entities = entities
+        self.component = component
 
     @asyncio.coroutine
     def get(self, request, entity_id):
         """Start a get request."""
-        player = self.entities.get(entity_id)
+        player = self.component.get_entity(entity_id)
         if player is None:
             status = 404 if request[KEY_AUTHENTICATED] else 401
             return web.Response(status=status)
diff --git a/homeassistant/components/microsoft_face.py b/homeassistant/components/microsoft_face.py
index 829c1124363..e61ed05ce10 100644
--- a/homeassistant/components/microsoft_face.py
+++ b/homeassistant/components/microsoft_face.py
@@ -161,7 +161,7 @@ def async_setup(hass, config):
             face.store.pop(g_id)
 
             entity = entities.pop(g_id)
-            yield from entity.async_remove()
+            hass.states.async_remove(entity.entity_id)
         except HomeAssistantError as err:
             _LOGGER.error("Can't delete group '%s' with error: %s", g_id, err)
 
diff --git a/homeassistant/components/remember_the_milk/__init__.py b/homeassistant/components/remember_the_milk/__init__.py
index 581380e3667..98cd937de3c 100644
--- a/homeassistant/components/remember_the_milk/__init__.py
+++ b/homeassistant/components/remember_the_milk/__init__.py
@@ -86,7 +86,7 @@ def _create_instance(hass, account_name, api_key, shared_secret,
                      token, stored_rtm_config, component):
     entity = RememberTheMilk(account_name, api_key, shared_secret,
                              token, stored_rtm_config)
-    component.add_entity(entity)
+    component.add_entities([entity])
     hass.services.register(
         DOMAIN, '{}_create_task'.format(account_name), entity.create_task,
         schema=SERVICE_SCHEMA_CREATE_TASK)
diff --git a/homeassistant/components/script.py b/homeassistant/components/script.py
index 7be8bd8175e..a45f8ba8930 100644
--- a/homeassistant/components/script.py
+++ b/homeassistant/components/script.py
@@ -156,7 +156,7 @@ def _async_process_config(hass, config, component):
     def service_handler(service):
         """Execute a service call to script.<script name>."""
         entity_id = ENTITY_ID_FORMAT.format(service.service)
-        script = component.entities.get(entity_id)
+        script = component.get_entity(entity_id)
         if script.is_on:
             _LOGGER.warning("Script %s already running.", entity_id)
             return
@@ -219,15 +219,11 @@ class ScriptEntity(ToggleEntity):
         """Turn script off."""
         self.script.async_stop()
 
-    def async_remove(self):
-        """Remove script from HASS.
-
-        This method must be run in the event loop and returns a coroutine.
-        """
+    @asyncio.coroutine
+    def async_will_remove_from_hass(self):
+        """Stop script and remove service when it will be removed from HASS."""
         if self.script.is_running:
             self.script.async_stop()
 
         # remove service
         self.hass.services.async_remove(DOMAIN, self.object_id)
-
-        return super().async_remove()
diff --git a/homeassistant/helpers/entity.py b/homeassistant/helpers/entity.py
index 61569b7cf53..e3816fdaa6f 100644
--- a/homeassistant/helpers/entity.py
+++ b/homeassistant/helpers/entity.py
@@ -15,8 +15,7 @@ from homeassistant.core import HomeAssistant, callback
 from homeassistant.config import DATA_CUSTOMIZE
 from homeassistant.exceptions import NoEntitySpecifiedError
 from homeassistant.util import ensure_unique_string, slugify
-from homeassistant.util.async import (
-    run_coroutine_threadsafe, run_callback_threadsafe)
+from homeassistant.util.async import run_callback_threadsafe
 
 _LOGGER = logging.getLogger(__name__)
 SLOW_UPDATE_WARNING = 10
@@ -66,9 +65,12 @@ class Entity(object):
     # this class. These may be used to customize the behavior of the entity.
     entity_id = None  # type: str
 
-    # Owning hass instance. Will be set by EntityComponent
+    # Owning hass instance. Will be set by EntityPlatform
     hass = None  # type: Optional[HomeAssistant]
 
+    # Owning platform instance. Will be set by EntityPlatform
+    platform = None
+
     # If we reported if this entity was slow
     _slow_reported = False
 
@@ -311,19 +313,13 @@ class Entity(object):
             if self.parallel_updates:
                 self.parallel_updates.release()
 
-    def remove(self) -> None:
-        """Remove entity from HASS."""
-        run_coroutine_threadsafe(
-            self.async_remove(), self.hass.loop
-        ).result()
-
     @asyncio.coroutine
-    def async_remove(self) -> None:
-        """Remove entity from async HASS.
-
-        This method must be run in the event loop.
-        """
-        self.hass.states.async_remove(self.entity_id)
+    def async_remove(self):
+        """Remove entity from Home Assistant."""
+        if self.platform is not None:
+            yield from self.platform.async_remove_entity(self.entity_id)
+        else:
+            self.hass.states.async_remove(self.entity_id)
 
     def _attr_setter(self, name, typ, attr, attrs):
         """Populate attributes based on properties."""
diff --git a/homeassistant/helpers/entity_component.py b/homeassistant/helpers/entity_component.py
index 9b25b8ddbd4..4a791d12e52 100644
--- a/homeassistant/helpers/entity_component.py
+++ b/homeassistant/helpers/entity_component.py
@@ -1,6 +1,7 @@
 """Helpers for components that manage entities."""
 import asyncio
 from datetime import timedelta
+from itertools import chain
 
 from homeassistant import config as conf_util
 from homeassistant.setup import async_prepare_setup_platform
@@ -9,7 +10,6 @@ from homeassistant.const import (
     DEVICE_DEFAULT_NAME)
 from homeassistant.core import callback, valid_entity_id
 from homeassistant.exceptions import HomeAssistantError, PlatformNotReady
-from homeassistant.loader import get_component
 from homeassistant.helpers import config_per_platform, discovery
 from homeassistant.helpers.entity import async_generate_entity_id
 from homeassistant.helpers.event import (
@@ -27,7 +27,15 @@ PLATFORM_NOT_READY_RETRIES = 10
 
 
 class EntityComponent(object):
-    """Helper class that will help a component manage its entities."""
+    """The EntityComponent manages platforms that manages entities.
+
+    This class has the following responsibilities:
+     - Process the configuration and set up a platform based component.
+     - Manage the platforms and their entities.
+     - Help extract the entities from a service call.
+     - Maintain a group that tracks all platform entities.
+     - Listen for discovery events for platforms related to the domain.
+    """
 
     def __init__(self, logger, domain, hass,
                  scan_interval=DEFAULT_SCAN_INTERVAL, group_name=None):
@@ -40,7 +48,6 @@ class EntityComponent(object):
         self.scan_interval = scan_interval
         self.group_name = group_name
 
-        self.entities = {}
         self.config = None
 
         self._platforms = {
@@ -49,6 +56,20 @@ class EntityComponent(object):
         self.async_add_entities = self._platforms['core'].async_add_entities
         self.add_entities = self._platforms['core'].add_entities
 
+    @property
+    def entities(self):
+        """Return an iterable that returns all entities."""
+        return chain.from_iterable(platform.entities.values() for platform
+                                   in self._platforms.values())
+
+    def get_entity(self, entity_id):
+        """Helper method to get an entity."""
+        for platform in self._platforms.values():
+            entity = platform.entities.get(entity_id)
+            if entity is not None:
+                return entity
+        return None
+
     def setup(self, config):
         """Set up a full entity component.
 
@@ -77,11 +98,10 @@ class EntityComponent(object):
 
         # Generic discovery listener for loading platform dynamically
         # Refer to: homeassistant.components.discovery.load_platform()
-        @callback
+        @asyncio.coroutine
         def component_platform_discovered(platform, info):
             """Handle the loading of a platform."""
-            self.hass.async_add_job(
-                self._async_setup_platform(platform, {}, info))
+            yield from self._async_setup_platform(platform, {}, info)
 
         discovery.async_listen_platform(
             self.hass, self.domain, component_platform_discovered)
@@ -107,13 +127,11 @@ class EntityComponent(object):
         This method must be run in the event loop.
         """
         if ATTR_ENTITY_ID not in service.data:
-            return [entity for entity in self.entities.values()
-                    if entity.available]
+            return [entity for entity in self.entities if entity.available]
 
-        return [self.entities[entity_id] for entity_id
-                in extract_entity_ids(self.hass, service, expand_group)
-                if entity_id in self.entities and
-                self.entities[entity_id].available]
+        entity_ids = set(extract_entity_ids(self.hass, service, expand_group))
+        return [entity for entity in self.entities
+                if entity.available and entity.entity_id in entity_ids]
 
     @asyncio.coroutine
     def _async_setup_platform(self, platform_type, platform_config,
@@ -193,80 +211,23 @@ class EntityComponent(object):
         finally:
             warn_task.cancel()
 
-    def add_entity(self, entity, platform=None, update_before_add=False):
-        """Add entity to component."""
-        return run_coroutine_threadsafe(
-            self.async_add_entity(entity, platform, update_before_add),
-            self.hass.loop
-        ).result()
-
-    @asyncio.coroutine
-    def async_add_entity(self, entity, platform=None, update_before_add=False):
-        """Add entity to component.
-
-        This method must be run in the event loop.
-        """
-        if entity is None or entity in self.entities.values():
-            return False
-
-        entity.hass = self.hass
-
-        # Update properties before we generate the entity_id
-        if update_before_add:
-            try:
-                yield from entity.async_device_update(warning=False)
-            except Exception:  # pylint: disable=broad-except
-                self.logger.exception("Error on device update!")
-                return False
-
-        # Write entity_id to entity
-        if getattr(entity, 'entity_id', None) is None:
-            object_id = entity.name or DEVICE_DEFAULT_NAME
-
-            if platform is not None and platform.entity_namespace is not None:
-                object_id = '{} {}'.format(platform.entity_namespace,
-                                           object_id)
-
-            entity.entity_id = async_generate_entity_id(
-                self.entity_id_format, object_id,
-                self.entities.keys())
-
-        # Make sure it is valid in case an entity set the value themselves
-        if entity.entity_id in self.entities:
-            raise HomeAssistantError(
-                'Entity id already exists: {}'.format(entity.entity_id))
-        elif not valid_entity_id(entity.entity_id):
-            raise HomeAssistantError(
-                'Invalid entity id: {}'.format(entity.entity_id))
-
-        self.entities[entity.entity_id] = entity
-
-        if hasattr(entity, 'async_added_to_hass'):
-            yield from entity.async_added_to_hass()
-
-        yield from entity.async_update_ha_state()
-
-        return True
-
-    def update_group(self):
-        """Set up and/or update component group."""
-        run_callback_threadsafe(
-            self.hass.loop, self.async_update_group).result()
-
     @callback
     def async_update_group(self):
         """Set up and/or update component group.
 
         This method must be run in the event loop.
         """
-        if self.group_name is not None:
-            ids = sorted(self.entities,
-                         key=lambda x: self.entities[x].name or x)
-            group = get_component('group')
-            group.async_set_group(
-                self.hass, slugify(self.group_name), name=self.group_name,
-                visible=False, entity_ids=ids
-            )
+        if self.group_name is None:
+            return
+
+        ids = [entity.entity_id for entity in
+               sorted(self.entities,
+                      key=lambda entity: entity.name or entity.entity_id)]
+
+        self.hass.components.group.async_set_group(
+            slugify(self.group_name), name=self.group_name,
+            visible=False, entity_ids=ids
+        )
 
     def reset(self):
         """Remove entities and reset the entity component to initial values."""
@@ -287,12 +248,17 @@ class EntityComponent(object):
         self._platforms = {
             'core': self._platforms['core']
         }
-        self.entities = {}
         self.config = None
 
         if self.group_name is not None:
-            group = get_component('group')
-            group.async_remove(self.hass, slugify(self.group_name))
+            self.hass.components.group.async_remove(slugify(self.group_name))
+
+    @asyncio.coroutine
+    def async_remove_entity(self, entity_id):
+        """Remove an entity managed by one of the platforms."""
+        for platform in self._platforms.values():
+            if entity_id in platform.entities:
+                yield from platform.async_remove_entity(entity_id)
 
     def prepare_reload(self):
         """Prepare reloading this entity component."""
@@ -323,7 +289,7 @@ class EntityComponent(object):
 
 
 class EntityPlatform(object):
-    """Keep track of entities for a single platform and stay in loop."""
+    """Manage the entities for a single platform."""
 
     def __init__(self, component, platform, scan_interval, parallel_updates,
                  entity_namespace):
@@ -333,7 +299,7 @@ class EntityPlatform(object):
         self.scan_interval = scan_interval
         self.parallel_updates = None
         self.entity_namespace = entity_namespace
-        self.platform_entities = []
+        self.entities = {}
         self._tasks = []
         self._async_unsub_polling = None
         self._process_updates = asyncio.Lock(loop=component.hass.loop)
@@ -391,40 +357,88 @@ class EntityPlatform(object):
         if not new_entities:
             return
 
-        @asyncio.coroutine
-        def async_process_entity(new_entity):
-            """Add entities to StateMachine."""
-            new_entity.parallel_updates = self.parallel_updates
-            ret = yield from self.component.async_add_entity(
-                new_entity, self, update_before_add=update_before_add
-            )
-            if ret:
-                self.platform_entities.append(new_entity)
+        component_entities = set(entity.entity_id for entity
+                                 in self.component.entities)
 
-        tasks = [async_process_entity(entity) for entity in new_entities]
+        tasks = [
+            self._async_add_entity(entity, update_before_add,
+                                   component_entities)
+            for entity in new_entities]
 
         yield from asyncio.wait(tasks, loop=self.component.hass.loop)
         self.component.async_update_group()
 
         if self._async_unsub_polling is not None or \
            not any(entity.should_poll for entity
-                   in self.platform_entities):
+                   in self.entities.values()):
             return
 
         self._async_unsub_polling = async_track_time_interval(
             self.component.hass, self._update_entity_states, self.scan_interval
         )
 
+    @asyncio.coroutine
+    def _async_add_entity(self, entity, update_before_add, component_entities):
+        """Helper method to add an entity to the platform."""
+        if entity is None:
+            raise ValueError('Entity cannot be None')
+
+        # Do nothing if entity has already been added based on unique id.
+        if entity in self.component.entities:
+            return
+
+        entity.hass = self.component.hass
+        entity.platform = self
+        entity.parallel_updates = self.parallel_updates
+
+        # Update properties before we generate the entity_id
+        if update_before_add:
+            try:
+                yield from entity.async_device_update(warning=False)
+            except Exception:  # pylint: disable=broad-except
+                self.component.logger.exception(
+                    "%s: Error on device update!", self.platform)
+                return
+
+        # Write entity_id to entity
+        if getattr(entity, 'entity_id', None) is None:
+            object_id = entity.name or DEVICE_DEFAULT_NAME
+
+            if self.entity_namespace is not None:
+                object_id = '{} {}'.format(self.entity_namespace,
+                                           object_id)
+
+            entity.entity_id = async_generate_entity_id(
+                self.component.entity_id_format, object_id,
+                component_entities)
+
+        # Make sure it is valid in case an entity set the value themselves
+        if not valid_entity_id(entity.entity_id):
+            raise HomeAssistantError(
+                'Invalid entity id: {}'.format(entity.entity_id))
+        elif entity.entity_id in component_entities:
+            raise HomeAssistantError(
+                'Entity id already exists: {}'.format(entity.entity_id))
+
+        self.entities[entity.entity_id] = entity
+        component_entities.add(entity.entity_id)
+
+        if hasattr(entity, 'async_added_to_hass'):
+            yield from entity.async_added_to_hass()
+
+        yield from entity.async_update_ha_state()
+
     @asyncio.coroutine
     def async_reset(self):
         """Remove all entities and reset data.
 
         This method must be run in the event loop.
         """
-        if not self.platform_entities:
+        if not self.entities:
             return
 
-        tasks = [entity.async_remove() for entity in self.platform_entities]
+        tasks = [self._async_remove_entity(entity_id)
+                 for entity_id in self.entities]
 
         yield from asyncio.wait(tasks, loop=self.component.hass.loop)
 
@@ -432,6 +446,28 @@ class EntityPlatform(object):
             self._async_unsub_polling()
             self._async_unsub_polling = None
 
+    @asyncio.coroutine
+    def async_remove_entity(self, entity_id):
+        """Remove entity id from platform."""
+        yield from self._async_remove_entity(entity_id)
+
+        # Clean up polling job if no longer needed
+        if (self._async_unsub_polling is not None and
+                not any(entity.should_poll for entity
+                        in self.entities.values())):
+            self._async_unsub_polling()
+            self._async_unsub_polling = None
+
+    @asyncio.coroutine
+    def _async_remove_entity(self, entity_id):
+        """Remove entity id from platform."""
+        entity = self.entities.pop(entity_id)
+
+        if hasattr(entity, 'async_will_remove_from_hass'):
+            yield from entity.async_will_remove_from_hass()
+
+        self.component.hass.states.async_remove(entity_id)
+
     @asyncio.coroutine
     def _update_entity_states(self, now):
         """Update the states of all the polling entities.
@@ -450,7 +486,7 @@ class EntityPlatform(object):
 
         with (yield from self._process_updates):
             tasks = []
-            for entity in self.platform_entities:
+            for entity in self.entities.values():
                 if not entity.should_poll:
                     continue
                 tasks.append(entity.async_update_ha_state(True))
diff --git a/tests/components/group/test_init.py b/tests/components/group/test_init.py
index 07dda7ff3b2..1dd848d3058 100644
--- a/tests/components/group/test_init.py
+++ b/tests/components/group/test_init.py
@@ -350,7 +350,7 @@ class TestComponentsGroup(unittest.TestCase):
 
         assert sorted(self.hass.states.entity_ids()) == \
             ['group.empty_group', 'group.second_group', 'group.test_group']
-        assert self.hass.bus.listeners['state_changed'] == 3
+        assert self.hass.bus.listeners['state_changed'] == 2
 
         with patch('homeassistant.config.load_yaml_config_file', return_value={
             'group': {
@@ -365,14 +365,6 @@ class TestComponentsGroup(unittest.TestCase):
         assert self.hass.states.entity_ids() == ['group.hello']
         assert self.hass.bus.listeners['state_changed'] == 1
 
-    def test_stopping_a_group(self):
-        """Test that a group correctly removes itself."""
-        grp = group.Group.create_group(
-            self.hass, 'light', ['light.test_1', 'light.test_2'])
-        assert self.hass.states.entity_ids() == ['group.light']
-        grp.stop()
-        assert self.hass.states.entity_ids() == []
-
     def test_changing_group_visibility(self):
         """Test that a group can be hidden and shown."""
         assert setup_component(self.hass, 'group', {
diff --git a/tests/helpers/test_entity.py b/tests/helpers/test_entity.py
index 637644ca5b3..e413fc145ca 100644
--- a/tests/helpers/test_entity.py
+++ b/tests/helpers/test_entity.py
@@ -388,3 +388,15 @@ def test_async_pararell_updates_with_two(hass):
     test_lock.release()
     yield from asyncio.sleep(0, loop=hass.loop)
     test_lock.release()
+
+
+@asyncio.coroutine
+def test_async_remove_no_platform(hass):
+    """Test async_remove method when no platform set."""
+    ent = entity.Entity()
+    ent.hass = hass
+    ent.entity_id = 'test.test'
+    yield from ent.async_update_ha_state()
+    assert len(hass.states.async_entity_ids()) == 1
+    yield from ent.async_remove()
+    assert len(hass.states.async_entity_ids()) == 0
diff --git a/tests/helpers/test_entity_component.py b/tests/helpers/test_entity_component.py
index 3d9ac2b2fd0..3109ea776bc 100644
--- a/tests/helpers/test_entity_component.py
+++ b/tests/helpers/test_entity_component.py
@@ -86,6 +86,7 @@ class TestHelpersEntityComponent(unittest.TestCase):
         assert len(self.hass.states.entity_ids()) == 0
 
         component.add_entities([EntityTest()])
+        self.hass.block_till_done()
 
         # group exists
         assert len(self.hass.states.entity_ids()) == 2
@@ -98,6 +99,7 @@ class TestHelpersEntityComponent(unittest.TestCase):
 
         # group extended
         component.add_entities([EntityTest(name='goodbye')])
+        self.hass.block_till_done()
 
         assert len(self.hass.states.entity_ids()) == 3
         group = self.hass.states.get('group.everyone')
@@ -214,7 +216,7 @@ class TestHelpersEntityComponent(unittest.TestCase):
 
         assert 0 == len(self.hass.states.entity_ids())
 
-        component.add_entities([None, EntityTest(unique_id='not_very_unique')])
+        component.add_entities([EntityTest(unique_id='not_very_unique')])
 
         assert 1 == len(self.hass.states.entity_ids())
 
@@ -671,3 +673,14 @@ def test_raise_error_on_update(hass):
 
     assert len(updates) == 1
     assert 1 in updates
+
+
+@asyncio.coroutine
+def test_async_remove_with_platform(hass):
+    """Remove an entity from a platform."""
+    component = EntityComponent(_LOGGER, DOMAIN, hass)
+    entity1 = EntityTest(name='test_1')
+    yield from component.async_add_entities([entity1])
+    assert len(hass.states.async_entity_ids()) == 1
+    yield from entity1.async_remove()
+    assert len(hass.states.async_entity_ids()) == 0