diff --git a/alembic/versions/c1d074288e99_create_environment_roles_table.py b/alembic/versions/c1d074288e99_create_environment_roles_table.py
new file mode 100644
index 00000000..ac1ea1ea
--- /dev/null
+++ b/alembic/versions/c1d074288e99_create_environment_roles_table.py
@@ -0,0 +1,38 @@
+"""create environment_roles table
+
+Revision ID: c1d074288e99
+Revises: 06aa23166ca9
+Create Date: 2018-09-06 13:40:12.332241
+
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision = 'c1d074288e99'
+down_revision = '06aa23166ca9'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('environment_roles',
+    sa.Column('id', postgresql.UUID(as_uuid=True), server_default=sa.text('uuid_generate_v4()'), nullable=False),
+    sa.Column('environment_id', postgresql.UUID(as_uuid=True), nullable=True),
+    sa.Column('role', sa.String(), nullable=True),
+    sa.Column('user_id', postgresql.UUID(as_uuid=True), nullable=True),
+    sa.ForeignKeyConstraint(['environment_id'], ['environments.id'], ),
+    sa.ForeignKeyConstraint(['user_id'], ['users.id'], ),
+    sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index('environments_role_user_environment', 'environment_roles', ['user_id', 'environment_id'], unique=True)
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_index('environments_role_user_environment', table_name='environment_roles')
+    op.drop_table('environment_roles')
+    # ### end Alembic commands ###
diff --git a/atst/domain/environments.py b/atst/domain/environments.py
index be007740..853eadb7 100644
--- a/atst/domain/environments.py
+++ b/atst/domain/environments.py
@@ -1,5 +1,6 @@
 from atst.database import db
 from atst.models.environment import Environment
+from atst.models.environment_role import EnvironmentRole, CSPRole
 
 
 class Environments(object):
@@ -16,3 +17,13 @@ class Environments(object):
             environment = Environment(project=project, name=name)
             db.session.add(environment)
         db.session.commit()
+
+    @classmethod
+    def add_member(cls, user, environment, member):
+        environment_user = EnvironmentRole(
+            user=member, environment=environment, role=CSPRole.NONSENSE_ROLE.value
+        )
+        db.session.add(environment_user)
+        db.session.commit()
+
+        return environment
diff --git a/atst/models/environment.py b/atst/models/environment.py
index 8e812635..5b091bac 100644
--- a/atst/models/environment.py
+++ b/atst/models/environment.py
@@ -14,3 +14,11 @@ class Environment(Base, TimestampsMixin):
 
     project_id = Column(ForeignKey("projects.id"))
     project = relationship("Project")
+
+    @property
+    def users(self):
+        return [r.user for r in self.roles]
+
+    @property
+    def num_users(self):
+        return len(self.users)
diff --git a/atst/models/environment_role.py b/atst/models/environment_role.py
new file mode 100644
index 00000000..7f36fe73
--- /dev/null
+++ b/atst/models/environment_role.py
@@ -0,0 +1,32 @@
+from enum import Enum
+from sqlalchemy import Index, ForeignKey, Column, String
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import relationship
+
+from atst.models import Base
+from .types import Id
+
+
+class CSPRole(Enum):
+    NONSENSE_ROLE = "nonesense_role"
+
+
+class EnvironmentRole(Base):
+    __tablename__ = "environment_roles"
+
+    id = Id()
+    environment_id = Column(UUID(as_uuid=True), ForeignKey("environments.id"))
+    environment = relationship("Environment", backref="roles")
+
+    role = Column(String())
+
+    user_id = Column(UUID(as_uuid=True), ForeignKey("users.id"))
+    user = relationship("User", backref="environment_roles")
+
+
+Index(
+    "environments_role_user_environment",
+    EnvironmentRole.user_id,
+    EnvironmentRole.environment_id,
+    unique=True,
+)
diff --git a/templates/workspace_projects.html b/templates/workspace_projects.html
index 0ad2d6ef..81aa8a11 100644
--- a/templates/workspace_projects.html
+++ b/templates/workspace_projects.html
@@ -39,7 +39,7 @@
             </a>
 
             <div class='project-list-item__environment__members'>
-              <div class='label'>0</div>
+              <div class='label'>{{ environment.num_users }}</div>
               <span>members</span>
             </div>
           </li>
diff --git a/tests/models/test_environments.py b/tests/models/test_environments.py
new file mode 100644
index 00000000..6bb4768f
--- /dev/null
+++ b/tests/models/test_environments.py
@@ -0,0 +1,18 @@
+from atst.domain.environments import Environments
+from atst.domain.workspaces import Workspaces
+from atst.domain.projects import Projects
+from tests.factories import RequestFactory, UserFactory
+
+
+def test_add_user_to_environment():
+    owner = UserFactory.create()
+    developer = UserFactory.from_atat_role("developer")
+
+    workspace = Workspaces.create(RequestFactory.create(creator=owner))
+    project = Projects.create(
+        workspace, "my test project", "It's mine.", ["dev", "staging", "prod"]
+    )
+    dev_environment = project.environments[0]
+
+    dev_environment = Environments.add_member(owner, dev_environment, developer)
+    assert developer in dev_environment.users