diff --git a/alembic/versions/08f2a640e9c2_add_uniqueness_contraint_to_environment_.py b/alembic/versions/08f2a640e9c2_add_uniqueness_contraint_to_environment_.py
new file mode 100644
index 00000000..56985f73
--- /dev/null
+++ b/alembic/versions/08f2a640e9c2_add_uniqueness_contraint_to_environment_.py
@@ -0,0 +1,28 @@
+"""add uniqueness contraint to environment within an application
+
+Revision ID: 08f2a640e9c2
+Revises: c487d91f1a26
+Create Date: 2019-12-16 10:43:12.331095
+
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision = '08f2a640e9c2' # pragma: allowlist secret
+down_revision = 'c487d91f1a26' # pragma: allowlist secret
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_unique_constraint('environments_name_application_id_key', 'environments', ['name', 'application_id'])
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_constraint('environments_name_application_id_key', 'environments', type_='unique')
+    # ### end Alembic commands ###
diff --git a/atst/domain/environments.py b/atst/domain/environments.py
index a1056623..fd5f3eb0 100644
--- a/atst/domain/environments.py
+++ b/atst/domain/environments.py
@@ -12,6 +12,7 @@ from atst.models import (
     CLIN,
 )
 from atst.domain.environment_roles import EnvironmentRoles
+from atst.utils import update_or_raise_already_exists_error
 
 from .exceptions import NotFoundError, DisabledError
 
@@ -21,7 +22,7 @@ class Environments(object):
     def create(cls, user, application, name):
         environment = Environment(application=application, name=name, creator=user)
         db.session.add(environment)
-        db.session.commit()
+        update_or_raise_already_exists_error(message="environment")
         return environment
 
     @classmethod
@@ -39,7 +40,8 @@ class Environments(object):
         if name is not None:
             environment.name = name
             db.session.add(environment)
-            db.session.commit()
+            update_or_raise_already_exists_error(message="environment")
+            return environment
 
     @classmethod
     def get(cls, environment_id):
diff --git a/atst/models/environment.py b/atst/models/environment.py
index 5fc642e5..115f3ed7 100644
--- a/atst/models/environment.py
+++ b/atst/models/environment.py
@@ -1,4 +1,4 @@
-from sqlalchemy import Column, ForeignKey, String, TIMESTAMP
+from sqlalchemy import Column, ForeignKey, String, TIMESTAMP, UniqueConstraint
 from sqlalchemy.orm import relationship
 from sqlalchemy.dialects.postgresql import JSONB
 from enum import Enum
@@ -38,6 +38,12 @@ class Environment(
         primaryjoin="and_(EnvironmentRole.environment_id == Environment.id, EnvironmentRole.deleted == False)",
     )
 
+    __table_args__ = (
+        UniqueConstraint(
+            "name", "application_id", name="environments_name_application_id_key"
+        ),
+    )
+
     class ProvisioningStatus(Enum):
         PENDING = "pending"
         COMPLETED = "completed"
diff --git a/tests/domain/test_environments.py b/tests/domain/test_environments.py
index 3aa5f547..298f2675 100644
--- a/tests/domain/test_environments.py
+++ b/tests/domain/test_environments.py
@@ -4,7 +4,7 @@ from uuid import uuid4
 
 from atst.domain.environments import Environments
 from atst.domain.environment_roles import EnvironmentRoles
-from atst.domain.exceptions import NotFoundError, DisabledError
+from atst.domain.exceptions import AlreadyExistsError, DisabledError, NotFoundError
 from atst.models.environment_role import CSPRole, EnvironmentRole
 
 from tests.factories import (
@@ -100,6 +100,27 @@ def test_update_environment():
     assert environment.name == "name 2"
 
 
+def test_create_does_not_duplicate_names_within_application():
+    application = ApplicationFactory.create()
+    name = "Your Environment"
+    user = application.portfolio.owner
+
+    assert Environments.create(user, application, name)
+    with pytest.raises(AlreadyExistsError):
+        Environments.create(user, application, name)
+
+
+def test_update_does_not_duplicate_names_within_application():
+    application = ApplicationFactory.create()
+    name = "Your Environment"
+    environment = EnvironmentFactory.create(application=application, name=name)
+    dupe_env = EnvironmentFactory.create(application=application)
+    user = application.portfolio.owner
+
+    with pytest.raises(AlreadyExistsError):
+        Environments.update(dupe_env, name)
+
+
 class EnvQueryTest:
     @property
     def NOW(self):