diff --git a/juju/application.py b/juju/application.py
new file mode 100644
index 0000000..8719a62
--- /dev/null
+++ b/juju/application.py
@@ -0,0 +1,391 @@
+import asyncio
+import logging
+
+from . import model
+from .client import client
+from .errors import JujuError
+from .placement import parse as parse_placement
+
+log = logging.getLogger(__name__)
+
+
+class Application(model.ModelEntity):
+    @property
+    def _unit_match_pattern(self):
+        return r'^{}.*$'.format(self.entity_id)
+
+    def on_unit_add(self, callable_):
+        """Add a "unit added" observer to this entity, which will be called
+        whenever a unit is added to this application.
+
+        """
+        self.model.add_observer(
+            callable_, 'unit', 'add', self._unit_match_pattern)
+
+    def on_unit_remove(self, callable_):
+        """Add a "unit removed" observer to this entity, which will be called
+        whenever a unit is removed from this application.
+
+        """
+        self.model.add_observer(
+            callable_, 'unit', 'remove', self._unit_match_pattern)
+
+    @property
+    def units(self):
+        return [
+            unit for unit in self.model.units.values()
+            if unit.application == self.name
+        ]
+
+    @property
+    def status(self):
+        """Get the application status, as set by the charm's leader.
+
+        """
+        return self.safe_data['status']['current']
+
+    @property
+    def status_message(self):
+        """Get the application status message, as set by the charm's leader.
+
+        """
+        return self.safe_data['status']['message']
+
+    @property
+    def tag(self):
+        return 'application-%s' % self.name
+
+    async def add_relation(self, local_relation, remote_relation):
+        """Add a relation to another application.
+
+        :param str local_relation: Name of relation on this application
+        :param str remote_relation: Name of relation on the other
+            application in the form '<application>[:<relation_name>]'
+
+        """
+        if ':' not in local_relation:
+            local_relation = '{}:{}'.format(self.name, local_relation)
+
+        return await self.model.add_relation(local_relation, remote_relation)
+
+    async def add_unit(self, count=1, to=None):
+        """Add one or more units to this application.
+
+        :param int count: Number of units to add
+        :param str to: Placement directive, e.g.::
+            '23' - machine 23
+            'lxc:7' - new lxc container on machine 7
+            '24/lxc/3' - lxc container 3 or machine 24
+
+            If None, a new machine is provisioned.
+
+        """
+        app_facade = client.ApplicationFacade.from_connection(self.connection)
+
+        log.debug(
+            'Adding %s unit%s to %s',
+            count, '' if count == 1 else 's', self.name)
+
+        result = await app_facade.AddUnits(
+            application=self.name,
+            placement=parse_placement(to) if to else None,
+            num_units=count,
+        )
+
+        return await asyncio.gather(*[
+            asyncio.ensure_future(self.model._wait_for_new('unit', unit_id))
+            for unit_id in result.units
+        ])
+
+    add_units = add_unit
+
+    def allocate(self, budget, value):
+        """Allocate budget to this application.
+
+        :param str budget: Name of budget
+        :param int value: Budget limit
+
+        """
+        raise NotImplementedError()
+
+    def attach(self, resource_name, file_path):
+        """Upload a file as a resource for this application.
+
+        :param str resource: Name of the resource
+        :param str file_path: Path to the file to upload
+
+        """
+        raise NotImplementedError()
+
+    def collect_metrics(self):
+        """Collect metrics on this application.
+
+        """
+        raise NotImplementedError()
+
+    async def destroy_relation(self, local_relation, remote_relation):
+        """Remove a relation to another application.
+
+        :param str local_relation: Name of relation on this application
+        :param str remote_relation: Name of relation on the other
+            application in the form '<application>[:<relation_name>]'
+
+        """
+        if ':' not in local_relation:
+            local_relation = '{}:{}'.format(self.name, local_relation)
+
+        app_facade = client.ApplicationFacade.from_connection(self.connection)
+
+        log.debug(
+            'Destroying relation %s <-> %s', local_relation, remote_relation)
+
+        return await app_facade.DestroyRelation([
+            local_relation, remote_relation])
+    remove_relation = destroy_relation
+
+    async def destroy_unit(self, *unit_names):
+        """Destroy units by name.
+
+        """
+        return await self.model.destroy_units(*unit_names)
+    destroy_units = destroy_unit
+
+    async def destroy(self):
+        """Remove this application from the model.
+
+        """
+        app_facade = client.ApplicationFacade.from_connection(self.connection)
+
+        log.debug(
+            'Destroying %s', self.name)
+
+        return await app_facade.Destroy(self.name)
+    remove = destroy
+
+    async def expose(self):
+        """Make this application publicly available over the network.
+
+        """
+        app_facade = client.ApplicationFacade.from_connection(self.connection)
+
+        log.debug(
+            'Exposing %s', self.name)
+
+        return await app_facade.Expose(self.name)
+
+    async def get_config(self):
+        """Return the configuration settings dict for this application.
+
+        """
+        app_facade = client.ApplicationFacade.from_connection(self.connection)
+
+        log.debug(
+            'Getting config for %s', self.name)
+
+        return (await app_facade.Get(self.name)).config
+
+    async def get_constraints(self):
+        """Return the machine constraints dict for this application.
+
+        """
+        app_facade = client.ApplicationFacade.from_connection(self.connection)
+
+        log.debug(
+            'Getting constraints for %s', self.name)
+
+        result = (await app_facade.Get(self.name)).constraints
+        return vars(result) if result else result
+
+    def get_actions(self, schema=False):
+        """Get actions defined for this application.
+
+        :param bool schema: Return the full action schema
+
+        """
+        raise NotImplementedError()
+
+    def get_resources(self, details=False):
+        """Return resources for this application.
+
+        :param bool details: Include detailed info about resources used by each
+            unit
+
+        """
+        raise NotImplementedError()
+
+    async def run(self, command, timeout=None):
+        """Run command on all units for this application.
+
+        :param str command: The command to run
+        :param int timeout: Time to wait before command is considered failed
+
+        """
+        action = client.ActionFacade.from_connection(self.connection)
+
+        log.debug(
+            'Running `%s` on all units of %s', command, self.name)
+
+        # TODO this should return a list of Actions
+        return await action.Run(
+            [self.name],
+            command,
+            [],
+            timeout,
+            [],
+        )
+
+    async def set_annotations(self, annotations):
+        """Set annotations on this application.
+
+        :param annotations map[string]string: the annotations as key/value
+            pairs.
+
+        """
+        log.debug('Updating annotations on application %s', self.name)
+
+        self.ann_facade = client.AnnotationsFacade.from_connection(
+            self.connection)
+
+        ann = client.EntityAnnotations(
+            entity=self.tag,
+            annotations=annotations,
+        )
+        return await self.ann_facade.Set([ann])
+
+    async def set_config(self, config, to_default=False):
+        """Set configuration options for this application.
+
+        :param config: Dict of configuration to set
+        :param bool to_default: Set application options to default values
+
+        """
+        app_facade = client.ApplicationFacade.from_connection(self.connection)
+
+        log.debug(
+            'Setting config for %s: %s', self.name, config)
+
+        return await app_facade.Set(self.name, config)
+
+    async def set_constraints(self, constraints):
+        """Set machine constraints for this application.
+
+        :param dict constraints: Dict of machine constraints
+
+        """
+        app_facade = client.ApplicationFacade.from_connection(self.connection)
+
+        log.debug(
+            'Setting constraints for %s: %s', self.name, constraints)
+
+        return await app_facade.SetConstraints(self.name, constraints)
+
+    def set_meter_status(self, status, info=None):
+        """Set the meter status on this status.
+
+        :param str status: Meter status, e.g. 'RED', 'AMBER'
+        :param str info: Extra info message
+
+        """
+        raise NotImplementedError()
+
+    def set_plan(self, plan_name):
+        """Set the plan for this application, effective immediately.
+
+        :param str plan_name: Name of plan
+
+        """
+        raise NotImplementedError()
+
+    async def unexpose(self):
+        """Remove public availability over the network for this application.
+
+        """
+        app_facade = client.ApplicationFacade.from_connection(self.connection)
+
+        log.debug(
+            'Unexposing %s', self.name)
+
+        return await app_facade.Unexpose(self.name)
+
+    def update_allocation(self, allocation):
+        """Update existing allocation for this application.
+
+        :param int allocation: The allocation to set
+
+        """
+        raise NotImplementedError()
+
+    async def upgrade_charm(
+            self, channel=None, force_series=False, force_units=False,
+            path=None, resources=None, revision=None, switch=None):
+        """Upgrade the charm for this application.
+
+        :param str channel: Channel to use when getting the charm from the
+            charm store, e.g. 'development'
+        :param bool force_series: Upgrade even if series of deployed
+            application is not supported by the new charm
+        :param bool force_units: Upgrade all units immediately, even if in
+            error state
+        :param str path: Uprade to a charm located at path
+        :param dict resources: Dictionary of resource name/filepath pairs
+        :param int revision: Explicit upgrade revision
+        :param str switch: Crossgrade charm url
+
+        """
+        # TODO: Support local upgrades
+        if path is not None:
+            raise NotImplementedError("path option is not implemented")
+        if resources is not None:
+            raise NotImplementedError("resources option is not implemented")
+
+        if switch is not None and revision is not None:
+            raise ValueError("switch and revision are mutually exclusive")
+
+        client_facade = client.ClientFacade.from_connection(self.connection)
+        app_facade = client.ApplicationFacade.from_connection(self.connection)
+
+        if switch is not None:
+            charm_url = switch
+            if not charm_url.startswith('cs:'):
+                charm_url = 'cs:' + charm_url
+        else:
+            charm_url = self.data['charm-url']
+            charm_url = charm_url.rpartition('-')[0]
+            if revision is not None:
+                charm_url = "%s-%d" % (charm_url, revision)
+            else:
+                charmstore = self.model.charmstore
+                entity = await charmstore.entity(charm_url, channel=channel)
+                charm_url = entity['Id']
+
+        if charm_url == self.data['charm-url']:
+            raise JujuError('already running charm "%s"' % charm_url)
+
+        await client_facade.AddCharm(
+            url=charm_url,
+            channel=channel
+        )
+
+        await app_facade.SetCharm(
+            application=self.entity_id,
+            channel=channel,
+            charm_url=charm_url,
+            config_settings=None,
+            config_settings_yaml=None,
+            force_series=force_series,
+            force_units=force_units,
+            resource_ids=None,
+            storage_constraints=None
+        )
+
+        await self.model.block_until(
+            lambda: self.data['charm-url'] == charm_url
+        )
+
+    async def get_metrics(self):
+        """Get metrics for this application's units.
+
+        :return: Dictionary of unit_name:metrics
+
+        """
+        return await self.model.get_metrics(self.tag)