This book examines the relationship between semi-presidentialism and democratic performance. Semi-presidentialism - where a constitution provides for both a directly elected president and a prime minister and cabinet responsible to the legislature - has become the regime type of choice for new democracies. There are now over 50 countries in the world with a semi-presidential constitution and the vast majority of these countries have chosen this form of government since the early 1990s. This book operationalises Shugart and Carey's distinction between president-parliamentarism - where the prime minister is responsible to both the legislature and to the directly elected president - and premier-presidentialism - where the prime minister is responsible to the legislature alone. The book shows that, all else equal, the president-parliamentary sub-type is more likely to be associated with a poorer democratic performance than its premier-presidential counterpart. The evidence is based on a mixed-method approach, including large-n comparative statistical studies of all semi-presidential democracies since 1919, as well as in-depth case studies. Comparative Politics is a series for students, teachers, and researchers of political science that deals with contemporary government and politics. Global in scope, books in the series are characterised by a stress on comparative analysis and strong methodological rigour. The series is published in association with the European Consortium for Political Research. For more information visit: www.essex.ac.uk/ecpr