diff --git a/backend/app/database.py b/backend/app/database.py
index 3a686d9..28018cd 100644
--- a/backend/app/database.py
+++ b/backend/app/database.py
@@ -285,6 +285,73 @@ def _run_migrations():
             END IF;
         END $$;
         """,
+        # Teams and multi-tenancy migration (009_teams.sql)
+        """
+        -- Create teams table
+        CREATE TABLE IF NOT EXISTS teams (
+            id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+            name VARCHAR(255) NOT NULL,
+            slug VARCHAR(255) NOT NULL UNIQUE,
+            description TEXT,
+            created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
+            updated_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
+            created_by VARCHAR(255) NOT NULL,
+            settings JSONB DEFAULT '{}'::jsonb,
+            CONSTRAINT check_team_slug_format CHECK (slug ~ '^[a-z0-9][a-z0-9-]*[a-z0-9]$' OR slug ~ '^[a-z0-9]$')
+        );
+        """,
+        """
+        -- Create team_memberships table
+        CREATE TABLE IF NOT EXISTS team_memberships (
+            id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+            team_id UUID NOT NULL REFERENCES teams(id) ON DELETE CASCADE,
+            user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+            role VARCHAR(20) NOT NULL DEFAULT 'member',
+            created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
+            invited_by VARCHAR(255),
+            CONSTRAINT unique_team_membership UNIQUE (team_id, user_id),
+            CONSTRAINT check_team_role CHECK (role IN ('owner', 'admin', 'member'))
+        );
+        """,
+        # Add team_id column to projects table
+        """
+        DO $$
+        BEGIN
+            IF NOT EXISTS (
+                SELECT 1 FROM information_schema.columns
+                WHERE table_name = 'projects' AND column_name = 'team_id'
+            ) THEN
+                ALTER TABLE projects ADD COLUMN team_id UUID REFERENCES teams(id) ON DELETE SET NULL;
+            END IF;
+        END $$;
+        """,
+        # Create indexes for teams
+        """
+        DO $$
+        BEGIN
+            IF NOT EXISTS (SELECT 1 FROM pg_indexes WHERE indexname = 'idx_teams_slug') THEN
+                CREATE INDEX idx_teams_slug ON teams(slug);
+            END IF;
+            IF NOT EXISTS (SELECT 1 FROM pg_indexes WHERE indexname = 'idx_teams_created_by') THEN
+                CREATE INDEX idx_teams_created_by ON teams(created_by);
+            END IF;
+            IF NOT EXISTS (SELECT 1 FROM pg_indexes WHERE indexname = 'idx_teams_created_at') THEN
+                CREATE INDEX idx_teams_created_at ON teams(created_at);
+            END IF;
+            IF NOT EXISTS (SELECT 1 FROM pg_indexes WHERE indexname = 'idx_team_memberships_team_id') THEN
+                CREATE INDEX idx_team_memberships_team_id ON team_memberships(team_id);
+            END IF;
+            IF NOT EXISTS (SELECT 1 FROM pg_indexes WHERE indexname = 'idx_team_memberships_user_id') THEN
+                CREATE INDEX idx_team_memberships_user_id ON team_memberships(user_id);
+            END IF;
+            IF NOT EXISTS (SELECT 1 FROM pg_indexes WHERE indexname = 'idx_team_memberships_role') THEN
+                CREATE INDEX idx_team_memberships_role ON team_memberships(role);
+            END IF;
+            IF NOT EXISTS (SELECT 1 FROM pg_indexes WHERE indexname = 'idx_projects_team_id') THEN
+                CREATE INDEX idx_projects_team_id ON projects(team_id);
+            END IF;
+        END $$;
+        """,
     ]
 
     with engine.connect() as conn: