"As political science has come to depend more and more on quantitative methods, with a significant focus on causal identification (put simply, "what causes what"), there has been a growing concern that the questions scholars address are getting smaller, shrinking to include only those topics for which the so-called "identification problem" can be satisfactorily solved. Yet even if this problem cannot yet be solved for many important and complex topics--demacy, inequality, violence, stability, and many more--there is much left to learn; in particular, clear theories that provide better insight into the central mechanisms at work. These theories can help orient new empirical work, thus fueling a virtuous cycle between empirical and theoretical insights. In this ambitious book. Ashworth et al address this key challenge in the field with a new vision of how to connect empirical and theoretical work, one rooted in the idea of "all else equal." Theory, the authors argue, implicitly rests of the idea of "all-else-equal," and it's precisely this question that empirical work attempts to confirm. Thus theory and empirics have an intrinsic connection, and in recognizing this scholars can bridge the gap between the two. The first part of the book examines the "all-else-equal" connection and goes on to show how how theoretical models yield empirical implications and how substantive identification is the lynch-pin of a credible research design. The second part then follows the progressive back-and-forth between theory and empirics in existing scholarship, breaking these interactions into five types: reinterpreting, elaboration, distinguishing, disentangling, and modeling the research design. Each chapter in this section provides concrete examples, discussing a handful of papers that illustrates the relevant interaction between theory and empirics. The overall goal of the book is to facilitate a closer and more productive interaction between theory and empirics in social science"--