diff --git a/awx/main/models/base.py b/awx/main/models/base.py
index 7baf81e93b..45cabc5a83 100644
--- a/awx/main/models/base.py
+++ b/awx/main/models/base.py
@@ -11,6 +11,7 @@ import os.path
 import yaml
 
 # Django
+from django.conf import settings
 from django.db import models
 from django.db import transaction
 from django.core.exceptions import ValidationError
@@ -405,10 +406,47 @@ class CommonTask(PrimordialModel):
     def can_cancel(self):
         return bool(self.status in ('pending', 'waiting', 'running'))
 
+    def _force_cancel(self):
+        # Update the status to 'canceled' if we can detect that the job
+        # really isn't running (i.e. celery has crashed or forcefully
+        # killed the worker).
+        task_statuses = ('STARTED', 'SUCCESS', 'FAILED', 'RETRY', 'REVOKED')
+        try:
+            taskmeta = self.celery_task
+            if not taskmeta or taskmeta.status not in task_statuses:
+                return
+            from celery import current_app
+            i = current_app.control.inspect()
+            for v in (i.active() or {}).values():
+                if taskmeta.task_id in [x['id'] for x in v]:
+                    return
+            for v in (i.reserved() or {}).values():
+                if taskmeta.task_id in [x['id'] for x in v]:
+                    return
+            for v in (i.revoked() or {}).values():
+                if taskmeta.task_id in [x['id'] for x in v]:
+                    return
+            for v in (i.scheduled() or {}).values():
+                if taskmeta.task_id in [x['id'] for x in v]:
+                    return
+            instance = self.__class__.objects.get(pk=self.pk)
+            if instance.can_cancel:
+                instance.status = 'canceled'
+                update_fields = ['status']
+                if not instance.result_traceback:
+                    instance.result_traceback = 'Forced cancel'
+                    update_fields.append('result_traceback')
+                instance.save(update_fields=update_fields)
+        except: # FIXME: Log this exception!
+            if settings.DEBUG:
+                raise
+
     def cancel(self):
-        # FIXME: Force cancel!
         if self.can_cancel:
             if not self.cancel_flag:
                 self.cancel_flag = True
                 self.save(update_fields=['cancel_flag'])
+            if settings.BROKER_URL.startswith('amqp://'):
+                self._force_cancel()
         return self.cancel_flag
+
diff --git a/awx/main/tasks.py b/awx/main/tasks.py
index 1981c79722..d198a406e0 100644
--- a/awx/main/tasks.py
+++ b/awx/main/tasks.py
@@ -294,7 +294,14 @@ class BaseTask(Task):
         output_replacements = []
         try:
             if not self.pre_run_check(instance, **kwargs):
-                return
+                if hasattr(settings, 'CELERY_UNIT_TEST'):
+                    return
+                else:
+                    # Stop the task chain and prevent starting the job if it has
+                    # already been canceled.
+                    instance = self.update_model(pk)
+                    status = instance.status
+                    raise RuntimeError('not starting %s task' % instance.status)
             instance = self.update_model(pk, status='running')
             kwargs['private_data_file'] = self.build_private_data_file(instance, **kwargs)
             kwargs['passwords'] = self.build_passwords(instance, **kwargs)
@@ -312,7 +319,8 @@ class BaseTask(Task):
                                          job_cwd=cwd, job_env=safe_env, result_stdout_file=stdout_filename)
             status, stdout = self.run_pexpect(instance, args, cwd, env, kwargs['passwords'], stdout_handle)
         except Exception:
-            tb = traceback.format_exc()
+            if status != 'canceled':
+                tb = traceback.format_exc()
         finally:
             if kwargs.get('private_data_file', ''):
                 try:
@@ -330,7 +338,10 @@ class BaseTask(Task):
         if status != 'successful' and not hasattr(settings, 'CELERY_UNIT_TEST'):
             # Raising an exception will mark the job as 'failed' in celery
             # and will stop a task chain from continuing to execute
-            raise Exception("Task %s(pk:%s) encountered an error" % (str(self.model.__class__), str(pk)))
+            if status == 'canceled':
+                raise Exception("Task %s(pk:%s) was canceled" % (str(self.model.__class__), str(pk)))
+            else:
+                raise Exception("Task %s(pk:%s) encountered an error" % (str(self.model.__class__), str(pk)))
 
 class RunJob(BaseTask):
     '''
@@ -477,7 +488,10 @@ class RunJob(BaseTask):
         '''
         Hook for checking job before running.
         '''
-        if job.status in ('pending', 'waiting'):
+        if job.cancel_flag:
+            job = self.update_model(job.pk, status='canceled')
+            return False
+        elif job.status in ('pending', 'waiting'):
             job = self.update_model(job.pk, status='pending')
             # Start another task to process job events.
             if settings.BROKER_URL.startswith('amqp://'):
@@ -486,9 +500,6 @@ class RunJob(BaseTask):
                     'job_id': job.id,
                 }, serializer='json')
             return True
-        elif job.cancel_flag:
-            job = self.update_model(job.pk, status='canceled')
-            return False
         else:
             return False