At present much of political science consists of a large body of formal theoretical work that remains largely unexplored empirically and an expanding use of sophisticated statistical techniques. While there are examples of noteworthy efforts to bridge the gap between these, there is still a need for much more cooperative work between formal theorists and empirical researchers in the discipline. This book explores how empirical analysis has, can, and should be used to evaluate formal models in political science. These developments, if combined, are potentially a basis for a new revolution in political science.