diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 3b1d6a0..52f25db 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -15,6 +15,10 @@ Unreleased
 **********
 * Nothing unreleased
 
+[1.4.0]
+*******
+* feat: Add parent_content_key field to Transaction model (ENT-8389)
+
 [1.3.3]
 *******
 * Upgrade requirements
diff --git a/docs/decisions/0008-parent-content-key.rst b/docs/decisions/0008-parent-content-key.rst
new file mode 100644
index 0000000..c3a784d
--- /dev/null
+++ b/docs/decisions/0008-parent-content-key.rst
@@ -0,0 +1,25 @@
+0008 ``parent_content_key`` Field
+#################################
+
+Status
+******
+**Accepted** (February 2024)
+
+Context
+*******
+Today, we store a ``Transaction.content_key`` field which points at the content into which a learner is enrolled.
+Currently in the openedx ecosystem that would be a "course run key". However, we'd also like to know the parent
+identifier for the content, most often the "course key" associated with a "course run key" within the openedx ecosystem.
+In some downstream systems and frontends which consume transaction data it is essential to know the parent content key,
+but dynamically fetching it from APIs can be slow when working with many transactions.
+
+Decision
+********
+We'll introduce a ``parent_content_key`` field to the ``Transaction`` model. Similarly to ``content_title``, this new
+field will essentially locally cache slow-changing data (content keys are arguably the slowest of slow-changing).
+
+Consequences
+************
+* Creating transactions will additionally be required to pass a ``parent_content_key``, but this should be
+  straightforward since they already pass ``content_title``, which is already co-located with the parent content key
+  (``course_key``) within the system of record.
diff --git a/openedx_ledger/__init__.py b/openedx_ledger/__init__.py
index 37b85e4..3f36aeb 100644
--- a/openedx_ledger/__init__.py
+++ b/openedx_ledger/__init__.py
@@ -1,4 +1,4 @@
 """
 A library that records transactions against a ledger, denominated in units of value.
 """
-__version__ = "1.3.3"
+__version__ = "1.4.0"
diff --git a/openedx_ledger/api.py b/openedx_ledger/api.py
index 78f8748..975995a 100644
--- a/openedx_ledger/api.py
+++ b/openedx_ledger/api.py
@@ -44,6 +44,7 @@ def create_transaction(
     lms_user_id=None,
     lms_user_email=None,
     content_key=None,
+    parent_content_key=None,
     content_title=None,
     subsidy_access_policy_uuid=None,
     state=models.TransactionStateChoices.CREATED,
@@ -65,6 +66,9 @@ def create_transaction(
         content_key (str, Optional):
             The identifier of the content into which the learner is enrolling. Skip if this does not represent a policy
             enrolling a learner into content.
+        parent_content_key (str, Optional):
+            Identifier for the parent of the content_key. Skip if this does not represent a policy enrolling a learner
+            into content.
         content_title (str, Optional):
             The title of the content into which the learner is enrolling. Skip if this does not represent a policy
             enrolling a learner into content or if the title is not readily available.
@@ -96,6 +100,7 @@ def create_transaction(
                 defaults={
                     "quantity": quantity,
                     "content_key": content_key,
+                    "parent_content_key": parent_content_key,
                     "content_title": content_title,
                     "lms_user_id": lms_user_id,
                     "lms_user_email": lms_user_email,
diff --git a/openedx_ledger/migrations/0010_transaction_parent_content_key.py b/openedx_ledger/migrations/0010_transaction_parent_content_key.py
new file mode 100644
index 0000000..ebcc10a
--- /dev/null
+++ b/openedx_ledger/migrations/0010_transaction_parent_content_key.py
@@ -0,0 +1,23 @@
+# Generated by Django 3.2.23 on 2024-02-15 16:22
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('openedx_ledger', '0009_add_email_and_title_to_transactions'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='historicaltransaction',
+            name='parent_content_key',
+            field=models.CharField(blank=True, db_index=True, help_text='Identifier for the parent of the content_key.  Also should be joinable with ContentMetadata.content_key in enterprise-catalog. In practice, this is the course key corresponding to a course run key.', max_length=255, null=True),
+        ),
+        migrations.AddField(
+            model_name='transaction',
+            name='parent_content_key',
+            field=models.CharField(blank=True, db_index=True, help_text='Identifier for the parent of the content_key.  Also should be joinable with ContentMetadata.content_key in enterprise-catalog. In practice, this is the course key corresponding to a course run key.', max_length=255, null=True),
+        ),
+    ]
diff --git a/openedx_ledger/models.py b/openedx_ledger/models.py
index 232aded..0cde6eb 100644
--- a/openedx_ledger/models.py
+++ b/openedx_ledger/models.py
@@ -363,6 +363,16 @@ class Meta:
             "The globally unique content identifier.  Joinable with ContentMetadata.content_key in enterprise-catalog."
         )
     )
+    parent_content_key = models.CharField(
+        max_length=255,
+        blank=True,
+        null=True,
+        db_index=True,
+        help_text=(
+            "Identifier for the parent of the content_key.  Also should be joinable with ContentMetadata.content_key "
+            "in enterprise-catalog. In practice, this is the course key corresponding to a course run key."
+        )
+    )
     content_title = models.CharField(
         max_length=255,
         blank=True,
diff --git a/openedx_ledger/test_utils/factories.py b/openedx_ledger/test_utils/factories.py
index 713cd5e..8f82559 100644
--- a/openedx_ledger/test_utils/factories.py
+++ b/openedx_ledger/test_utils/factories.py
@@ -45,7 +45,8 @@ class Meta:
     ledger = factory.Iterator(Ledger.objects.all())
     lms_user_id = factory.Faker("random_int", min=1, max=1000)
     lms_user_email = factory.Faker("email")
-    content_key = factory.Faker("lexify", text="???+?????101")
+    content_key = factory.LazyAttribute(lambda tx: f"course-v1:{tx.parent_content_key}+2023")
+    parent_content_key = factory.Faker("lexify", text="???+?????101")
     content_title = factory.Faker("lexify", text="???: ?????? ???")
 
 
diff --git a/tests/test_models.py b/tests/test_models.py
index 9c62377..b277544 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -43,6 +43,7 @@ def setUp(self):
             lms_user_id=3,
             lms_user_email='user@example.com',
             content_key="course-v1:edX+test+course.3",
+            parent_content_key="edX+test",
             content_title="Edx: test course 3",
             quantity=-10,
             state=models.TransactionStateChoices.PENDING,