Lahr (officially Lahr/Schwarzwald since 30 September 1978) ((German: [laːɐ̯] ); Low Alemannic: Lohr) is a city in western Baden-Württemberg, Germany, approximately 50 km north of Freiburg im Breisgau, 40 km southeast of Strasbourg, and 95 km southwest of Karlsruhe. It is the second largest city in Ortenau (district) after Offenburg, and serves as an intermediate economic centre for the cities and towns of Ettenheim , Friesenheim, Kappel-Grafenhausen , Kippenheim , Mahlberg, Meißenheim, Ringsheim, Rust, Schuttertal, Schwanau and Seelbach.

The population of Lahr passed the 20,000 mark in the mid-1950s. When the new body of Municipal Law for Baden-Württemberg came into effect on April 1, 1956, the city was therefore immediately accorded Große Kreisstadt status. In addition, Lahr cooperates with the town of Kippenheim in administrative matters.

Lahr is located on the western edge of the Black Forest where the Schutter Valley merges with the Upper Rhine River Plains from the east.