diff --git a/icekit_events/migrations/0011_auto_20161128_1049.py b/icekit_events/migrations/0011_auto_20161128_1049.py
new file mode 100644
index 0000000..4fa680f
--- /dev/null
+++ b/icekit_events/migrations/0011_auto_20161128_1049.py
@@ -0,0 +1,35 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('icekit_events', '0010_eventbase_is_drop_in'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='eventbase',
+            name='derived_from',
+            field=models.ForeignKey(related_name='derivitives', editable=False, blank=True, to='icekit_events.EventBase', on_delete=django.db.models.deletion.SET_NULL, null=True),
+        ),
+        migrations.AlterField(
+            model_name='eventbase',
+            name='part_of',
+            field=models.ForeignKey(related_name='contained_events', help_text=b'If this event is part of another event, select it here.', blank=True, to='icekit_events.EventBase', on_delete=django.db.models.deletion.SET_NULL, null=True),
+        ),
+        migrations.AlterField(
+            model_name='eventbase',
+            name='primary_type',
+            field=models.ForeignKey(related_name='events', help_text=b'The primary type of this event: Talk, workshop, etc. Only public Event Types can be primary.', blank=True, to='icekit_events.EventType', on_delete=django.db.models.deletion.SET_NULL, null=True),
+        ),
+        migrations.AlterField(
+            model_name='occurrence',
+            name='generator',
+            field=models.ForeignKey(to='icekit_events.EventRepeatsGenerator', blank=True, on_delete=django.db.models.deletion.SET_NULL, null=True),
+        ),
+    ]
diff --git a/icekit_events/models.py b/icekit_events/models.py
index f4203bd..d9c7836 100644
--- a/icekit_events/models.py
+++ b/icekit_events/models.py
@@ -227,12 +227,13 @@ class EventBase(PolymorphicModel, AbstractBaseModel, PublishingModel,
                   "public Event Types can be primary.",
         limit_choices_to={'is_public': True},
         related_name="events",
+        on_delete=models.SET_NULL,
     )
     secondary_types = models.ManyToManyField(
         EventType, blank=True,
         help_text="Additional/internal types: Education or members events, "
                   "for example.",
-        related_name="secondary_events",
+        related_name="secondary_events"
     ) # use all_types to get the union of primary and secondary types
 
     part_of = models.ForeignKey(
@@ -241,7 +242,8 @@ class EventBase(PolymorphicModel, AbstractBaseModel, PublishingModel,
         db_index=True,
         related_name="contained_events",
         null=True,
-        help_text="If this event is part of another event, select it here."
+        help_text="If this event is part of another event, select it here.",
+        on_delete=models.SET_NULL
     ) # access visible contained_events via get_contained_events()
     derived_from = models.ForeignKey(
         'self',
@@ -250,6 +252,7 @@ class EventBase(PolymorphicModel, AbstractBaseModel, PublishingModel,
         editable=False,
         null=True,
         related_name='derivitives',
+        on_delete=models.SET_NULL
     )
 
     show_in_calendar = models.BooleanField(
@@ -562,6 +565,7 @@ class EventRepeatsGenerator(AbstractBaseModel):
         db_index=True,
         editable=False,
         related_name='repeat_generators',
+        on_delete=models.CASCADE
     )
     recurrence_rule = RecurrenceRuleField(
         blank=True,
@@ -844,10 +848,13 @@ class Occurrence(AbstractBaseModel):
         db_index=True,
         editable=False,
         related_name='occurrences',
+        on_delete=models.CASCADE
     )
     generator = models.ForeignKey(
         EventRepeatsGenerator,
-        blank=True, null=True)
+        blank=True, null=True,
+        on_delete=models.SET_NULL
+    )
     start = models.DateTimeField(
         db_index=True)
     end = models.DateTimeField(
diff --git a/icekit_events/plugins/links/models.py b/icekit_events/plugins/links/models.py
index 47c3f50..3be26a3 100644
--- a/icekit_events/plugins/links/models.py
+++ b/icekit_events/plugins/links/models.py
@@ -3,7 +3,7 @@
 
 
 class EventLink(AbstractLinkItem):
-    item = models.ForeignKey("icekit_events.EventBase")
+    item = models.ForeignKey("icekit_events.EventBase", on_delete=models.CASCADE)
 
     class Meta:
         verbose_name = "Event link"