This paper compares German and American approaches to land-use regulation. Conclusions are derived from a review of regulatory documents and expert interviews conducted in the German city of Stuttgart. The analysis shows that in the United States, the zoning approach is most commonly based on the assumption of exclusivity (i.e., each land-use district is suitable for only a single type of human activity, such as residential, business or industrial); whereas in Germany the prevailing principle is that of predominance (i.e., each land-use district is suitable for multiple types of activity and most districts end up essentially mixed-use). Thus, although the names of the land-use categories used in both countries are similar, their definitions – the types of activities they permit – are starkly different. The paper concludes that zoning reform in the United States must start with a fundamental rethinking of the definitions behind our standard zoning categories and recommends further learning from European nations.