diff --git a/moto/cognitoidp/models.py b/moto/cognitoidp/models.py
index 96b23a404..2394c64ee 100644
--- a/moto/cognitoidp/models.py
+++ b/moto/cognitoidp/models.py
@@ -14,6 +14,7 @@ from jose import jws
 
 from moto.compat import OrderedDict
 from moto.core import BaseBackend, BaseModel
+from moto.core import ACCOUNT_ID as DEFAULT_ACCOUNT_ID
 from .exceptions import (
     GroupExistsException,
     NotAuthorizedError,
@@ -69,6 +70,9 @@ class CognitoIdpUserPool(BaseModel):
     def __init__(self, region, name, extended_config):
         self.region = region
         self.id = "{}_{}".format(self.region, str(uuid.uuid4().hex))
+        self.arn = "arn:aws:cognito-idp:{}:{}:userpool/{}".format(
+            self.region, DEFAULT_ACCOUNT_ID, self.id
+        )
         self.name = name
         self.status = None
         self.extended_config = extended_config or {}
@@ -91,6 +95,7 @@ class CognitoIdpUserPool(BaseModel):
     def _base_json(self):
         return {
             "Id": self.id,
+            "Arn": self.arn,
             "Name": self.name,
             "Status": self.status,
             "CreationDate": time.mktime(self.creation_date.timetuple()),
diff --git a/tests/test_cognitoidp/test_cognitoidp.py b/tests/test_cognitoidp/test_cognitoidp.py
index 2f7ed11e5..d37cf7d5c 100644
--- a/tests/test_cognitoidp/test_cognitoidp.py
+++ b/tests/test_cognitoidp/test_cognitoidp.py
@@ -27,6 +27,11 @@ def test_create_user_pool():
 
     result["UserPool"]["Id"].should_not.be.none
     result["UserPool"]["Id"].should.match(r"[\w-]+_[0-9a-zA-Z]+")
+    result["UserPool"]["Arn"].should.equal(
+        "arn:aws:cognito-idp:us-west-2:{}:userpool/{}".format(
+            ACCOUNT_ID, result["UserPool"]["Id"]
+        )
+    )
     result["UserPool"]["Name"].should.equal(name)
     result["UserPool"]["LambdaConfig"]["PreSignUp"].should.equal(value)