Research focusing on the biodiversity potential of green roofs has led to an amendment in building and construction law in Basel, Switzerland. As part of the city’s biodiversity strategy, green roofs are now mandatory on new buildings with flat roofs, and guidance is provided for the creation of different plant and animal habitats on the green roofs. Design criteria for the creation of these habitats include varying the substrate thickness and using natural soils from nearby areas. (Studies of green roofs in Zurich, Switzerland, have shown that natural soils can benefit biodiversity through their suitability for locally and regionally endangered species.) The design and construction of green roofs to re-create habitats require close cooperation among all specialists involved. Research and comprehensive planning are also important for creating space on roofs for urban wildlife.