The Dortmund Stadtbahn is a light rail system in the German city of Dortmund and is integrated in the Rhine-Ruhr Stadtbahn network. Its network consists of eight lines and is operated by Dortmunder Stadtwerke, which is operating under the brand DSW21 since 2005.

The Rhine-Ruhr Stadtbahn is an umbrella system of all of the Stadtbahn lines included in the integrated public transport network of the Verkehrsverbund Rhein-Ruhr (VRR), which covers the Rhine-Ruhr metropolitan area in western Germany. It does not include the Cologne and Bonn Stadtbahn systems, which are integrated in the Verkehrsverbund Rhein-Sieg (VRS).