This article examines patterns of institutional change in Latin America. It argues that unlike advanced industrialized democracies, where institutions evolve gradually and wholesale change is rare, many new democracies in Latin America are characterized by serial displacement, in which constitutions, electoral rules, and other institutions change both radically and frequently. Serial displacement is a product of extreme uncertainty and frequent incongruence between formal rule-makers and real power holders, which, in turn, are a product of regime instability, electoral volatility, frequent institutional borrowing, social inequality, and rapid institutional design. The article also examines how variation in enforcement affects institutional change. It argues that limited enforcement is often a source of institutional stability, and that varying levels of enforcement can be a substantively important source of institutional change. Because the activation of formal rules via enforcement is often easier than legal change, it may provide a useful focal point for civil society activism.