Few of Juan J. Linz?s works have generated as much debate and controversy as those on the relative merits of presidential versus parliamentary government. At a time when the countries of Central and Eastern Europe as well as those of the former Soviet Union are freeing themselves from the single-party system and questioning the evolution of their political institutions, Linz focuses on the perils of presidential systems and praises the merits of parliamentary government. Linz does not argue that democracies under a presidential system cannot be stable. Rather, he argues that the structural characteristics of presidential systems lead them to crises. By contrast, he argues, crises in parliamentary systems are governmental crises, whereas crises in presidential systems are liable to become regime crises. Linz?s stated preference for presidential government has been the subject of much debate and criticism. However, many authors have drawn additional lessons from the practice of presidential government, especially in Latin America. They analyzed in depth the various explanatory factors proposed by Linz were not sufficient to explain the instability that characterizes presidential systems. Instead, they have sought other institutional causes, including the configuration of political parties. In addition, they have also taken into account political, economic, and social factors.