diff --git a/homeassistant/components/notify/__init__.py b/homeassistant/components/notify/__init__.py
index 5bd99678f80..e56dfa5586d 100644
--- a/homeassistant/components/notify/__init__.py
+++ b/homeassistant/components/notify/__init__.py
@@ -42,7 +42,7 @@ PLATFORM_SCHEMA = vol.Schema({
 NOTIFY_SERVICE_SCHEMA = vol.Schema({
     vol.Required(ATTR_MESSAGE): cv.template,
     vol.Optional(ATTR_TITLE): cv.template,
-    vol.Optional(ATTR_TARGET): cv.string,
+    vol.Optional(ATTR_TARGET): vol.All(cv.ensure_list, [cv.string]),
     vol.Optional(ATTR_DATA): dict,
 })
 
diff --git a/homeassistant/components/notify/aws_lambda.py b/homeassistant/components/notify/aws_lambda.py
index 3e3003763ea..9ac9c4cbc18 100644
--- a/homeassistant/components/notify/aws_lambda.py
+++ b/homeassistant/components/notify/aws_lambda.py
@@ -79,9 +79,6 @@ class AWSLambda(BaseNotificationService):
             _LOGGER.info("At least 1 target is required")
             return
 
-        if not isinstance(targets, list):
-            targets = [targets]
-
         for target in targets:
             cleaned_kwargs = dict((k, v) for k, v in kwargs.items() if v)
             payload = {"message": message}
diff --git a/homeassistant/components/notify/aws_sns.py b/homeassistant/components/notify/aws_sns.py
index 88233234eca..fb6ae8984c6 100644
--- a/homeassistant/components/notify/aws_sns.py
+++ b/homeassistant/components/notify/aws_sns.py
@@ -70,9 +70,6 @@ class AWSSNS(BaseNotificationService):
             _LOGGER.info("At least 1 target is required")
             return
 
-        if not isinstance(targets, list):
-            targets = [targets]
-
         message_attributes = {k: {"StringValue": json.dumps(v),
                                   "DataType": "String"}
                               for k, v in kwargs.items() if v}
diff --git a/homeassistant/components/notify/aws_sqs.py b/homeassistant/components/notify/aws_sqs.py
index a1ddbcea3dd..edd8c4bec69 100644
--- a/homeassistant/components/notify/aws_sqs.py
+++ b/homeassistant/components/notify/aws_sqs.py
@@ -69,9 +69,6 @@ class AWSSQS(BaseNotificationService):
             _LOGGER.info("At least 1 target is required")
             return
 
-        if not isinstance(targets, list):
-            targets = [targets]
-
         for target in targets:
             cleaned_kwargs = dict((k, v) for k, v in kwargs.items() if v)
             message_body = {"message": message}
diff --git a/homeassistant/components/notify/html5.py b/homeassistant/components/notify/html5.py
index 0cf7028351b..a868552d051 100644
--- a/homeassistant/components/notify/html5.py
+++ b/homeassistant/components/notify/html5.py
@@ -359,8 +359,6 @@ class HTML5NotificationService(BaseNotificationService):
 
         if not targets:
             targets = self.registrations.keys()
-        elif not isinstance(targets, list):
-            targets = [targets]
 
         for target in targets:
             info = self.registrations.get(target)
diff --git a/homeassistant/components/notify/message_bird.py b/homeassistant/components/notify/message_bird.py
index 3a2770a65b5..5e7cc9eaf17 100644
--- a/homeassistant/components/notify/message_bird.py
+++ b/homeassistant/components/notify/message_bird.py
@@ -58,9 +58,6 @@ class MessageBirdNotificationService(BaseNotificationService):
             _LOGGER.error('No target specified.')
             return
 
-        if not isinstance(targets, list):
-            targets = [targets]
-
         for target in targets:
             try:
                 self.client.message_create(self.sender,
diff --git a/homeassistant/components/notify/pushbullet.py b/homeassistant/components/notify/pushbullet.py
index d5402548508..71b3f227e9b 100644
--- a/homeassistant/components/notify/pushbullet.py
+++ b/homeassistant/components/notify/pushbullet.py
@@ -87,10 +87,6 @@ class PushBulletNotificationService(BaseNotificationService):
             _LOGGER.info('Sent notification to self')
             return
 
-        # Make list if not so
-        if not isinstance(targets, list):
-            targets = [targets]
-
         # Main loop, Process all targets specified
         for target in targets:
             try:
diff --git a/homeassistant/components/notify/pushover.py b/homeassistant/components/notify/pushover.py
index c0a067fe918..bd7542c21cd 100644
--- a/homeassistant/components/notify/pushover.py
+++ b/homeassistant/components/notify/pushover.py
@@ -61,13 +61,15 @@ class PushoverNotificationService(BaseNotificationService):
 
         data['title'] = kwargs.get(ATTR_TITLE, ATTR_TITLE_DEFAULT)
 
-        target = kwargs.get(ATTR_TARGET)
-        if target is not None:
-            data['device'] = target
+        targets = kwargs.get(ATTR_TARGET)
 
-        try:
-            self.pushover.send_message(message, **data)
-        except ValueError as val_err:
-            _LOGGER.error(str(val_err))
-        except RequestError:
-            _LOGGER.exception('Could not send pushover notification')
+        for target in targets:
+            if target is not None:
+                data['device'] = target
+
+            try:
+                self.pushover.send_message(message, **data)
+            except ValueError as val_err:
+                _LOGGER.error(str(val_err))
+            except RequestError:
+                _LOGGER.exception('Could not send pushover notification')
diff --git a/homeassistant/components/notify/rest.py b/homeassistant/components/notify/rest.py
index 0a82b8d5d72..a7d31593ce3 100644
--- a/homeassistant/components/notify/rest.py
+++ b/homeassistant/components/notify/rest.py
@@ -75,8 +75,10 @@ class RestNotificationService(BaseNotificationService):
             data[self._title_param_name] = kwargs.get(ATTR_TITLE,
                                                       ATTR_TITLE_DEFAULT)
 
-        if self._target_param_name is not None:
-            data[self._target_param_name] = kwargs.get(ATTR_TARGET)
+        if self._target_param_name is not None and ATTR_TARGET in kwargs:
+            # Target is a list as of 0.29 and we don't want to break existing
+            # integrations, so just return the first target in the list.
+            data[self._target_param_name] = kwargs[ATTR_TARGET][0]
 
         if self._method == 'POST':
             response = requests.post(self._resource, data=data, timeout=10)
diff --git a/homeassistant/components/notify/services.yaml b/homeassistant/components/notify/services.yaml
index 419a796199a..a3980f658ea 100644
--- a/homeassistant/components/notify/services.yaml
+++ b/homeassistant/components/notify/services.yaml
@@ -11,9 +11,9 @@ notify:
       example: 'Your Garage Door Friend'
 
     target:
-      description: Target of the notification. Optional depending on the platform
+      description: An array of targets to send the notification to. Optional depending on the platform.
       example: platform specific
 
     data:
-      description: Extended information for notification. Optional depending on the platform
+      description: Extended information for notification. Optional depending on the platform.
       example: platform specific
diff --git a/homeassistant/components/notify/slack.py b/homeassistant/components/notify/slack.py
index aded8cd56a9..75ebb9b26fe 100644
--- a/homeassistant/components/notify/slack.py
+++ b/homeassistant/components/notify/slack.py
@@ -9,7 +9,7 @@ import logging
 import voluptuous as vol
 
 from homeassistant.components.notify import (
-    PLATFORM_SCHEMA, BaseNotificationService)
+    ATTR_TARGET, PLATFORM_SCHEMA, BaseNotificationService)
 from homeassistant.const import (
     CONF_API_KEY, CONF_USERNAME, CONF_ICON)
 import homeassistant.helpers.config_validation as cv
@@ -68,16 +68,19 @@ class SlackNotificationService(BaseNotificationService):
         """Send a message to a user."""
         import slacker
 
-        channel = kwargs.get('target') or self._default_channel
+        targets = kwargs.get(ATTR_TARGET, [self._default_channel])
+
         data = kwargs.get('data')
         attachments = data.get('attachments') if data else None
 
-        try:
-            self.slack.chat.post_message(channel, message,
-                                         as_user=self._as_user,
-                                         username=self._username,
-                                         icon_emoji=self._icon,
-                                         attachments=attachments,
-                                         link_names=True)
-        except slacker.Error as err:
-            _LOGGER.error("Could not send slack notification. Error: %s", err)
+        for target in targets:
+            try:
+                self.slack.chat.post_message(target, message,
+                                             as_user=self._as_user,
+                                             username=self._username,
+                                             icon_emoji=self._icon,
+                                             attachments=attachments,
+                                             link_names=True)
+            except slacker.Error as err:
+                _LOGGER.error("Could not send slack notification. Error: %s",
+                              err)
diff --git a/homeassistant/components/notify/twilio_sms.py b/homeassistant/components/notify/twilio_sms.py
index 8e59cf6d20c..d7e78ac7d1a 100644
--- a/homeassistant/components/notify/twilio_sms.py
+++ b/homeassistant/components/notify/twilio_sms.py
@@ -57,9 +57,6 @@ class TwilioSMSNotificationService(BaseNotificationService):
             _LOGGER.info("At least 1 target is required")
             return
 
-        if not isinstance(targets, list):
-            targets = [targets]
-
         for target in targets:
             self.client.messages.create(to=target, body=message,
                                         from_=self.from_number)
diff --git a/tests/components/notify/test_group.py b/tests/components/notify/test_group.py
index f1289a3dec1..e1c6d9f5bd4 100644
--- a/tests/components/notify/test_group.py
+++ b/tests/components/notify/test_group.py
@@ -74,7 +74,7 @@ class TestNotifyGroup(unittest.TestCase):
         data = self.events[-1].data
         assert {
             'message': 'Hello',
-            'target': 'unnamed device',
+            'target': ['unnamed device'],
             'title': 'Test notification',
             'data': {'hello': 'world', 'test': 'message'}
         } == data