This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book compares and contrasts the range of compulsory property acquisition laws and practices across the globe as applied to the goal of increasing densification. It provides a cross-national perspective on the circumstances and manner under which compulsory acquisition for densification takes place. The book describes the role of compulsory property acquisition as a central factor in enabling Montréal City to accommodate densification of a former industrial area while also preserving the area's identity and achieving social sustainability. The issue of property rights compensation is a starting point for wider consideration of critical questions concerning the ways in which compulsory acquisition is used to increase urban densification. Compulsory property acquisition is a politically contentious and controversial policy, as it involves some extra-market taking of property right.