Molenbeek-Saint-Jean or Sint-Jans-Molenbeek, often simply called Molenbeek, is one of the 19 municipalities of the Brussels-Capital Region, Belgium. Located in the western part of the region, it is bordered by the City of Brussels, from which it is separated by the Brussels–Charleroi Canal, as well as by the municipalities of Anderlecht, Berchem-Sainte-Agathe, Dilbeek, Jette, and Koekelberg. The Molenbeek brook, from which it takes its name, flows through the municipality. In common with all of Brussels' municipalities, it is legally bilingual (French–Dutch).

Brussels, officially the Brussels-Capital Region, is a region of Belgium comprising 19 municipalities, including the City of Brussels, which is the capital of Belgium. The Brussels-Capital Region is located in the central portion of the country and is a part of both the French Community of Belgium and the Flemish Community, but is separate from the Flemish Region and the Walloon Region, located less than 4 kilometres (2.5 mi) to the south. Historically Dutch-speaking, Brussels saw a language shift to French from the late 19th century. Nowadays, the Brussels-Capital Region is officially bilingual in French and Dutch, although French is the majority language and lingua franca. Brussels is also increasingly becoming multilingual. English is spoken widely and many migrants and expatriates speak other languages as well.