'Waldner equips qualitative researchers with a shared language for making causal explanations explicit, debatable, and cumulative across cases, subfields, disciplines, and generations. The payoff of rigorous standards, he shows, is liberation, not constraint: scholars gain the questions they must ask of one another's work-and their own-to deepen what we know.' Jake Bowers, Professor in the Departments of Political Science and Statistics, University of Illinois at Urbana-Champaign 'In this outstanding book, David Waldner argues that process tracing-like detective work-is critical to making compelling inferences about causality in the social sciences but concerns about confounding and other common sources of bias often receive too little attention. Waldner offers important remedies and criteria that will help scholars marry the best of qualitative and quantitative traditions.' Thad Dunning, Author of 'Natural Experiments in the Social Sciences: A Design-Based Approach' and Robson Professor of Political Science, University of California, Berkeley 'A ground-breaking blend of causal analysis common in quantitative methods, and the focus on explanation prevalent in qualitative approaches. David Waldner's precise, erudite reasoning shows how this merger will help scholars better understand why the world is the way it is. A great achievement.' Sean Gailmard, Author of 'Agents of Empire: Imperial Governance and the Making of American Political Institutions' and Herman Royer Professor of Political Economy, University of California, Berkeley 'This book is a monumental achievement. With his characteristic philosophical and methodological erudition, Waldner reaffirms our belief in the possibility of unit-level causal inference. He puts the so-called 'credibility revolution' in conversation with qualitative methods. In so doing, Waldner advances theoretical and empirical standards for case study research that will strengthen the next generation of scholarship oriented towards uncovering causal processes.' Ezequiel Gonzalez-Ocantos, Professor of Comparative and Judicial Politics, University of Oxford 'Waldner breaks new ground by formulating a notion of causal inference suited to qualitative case studies and specifying a set of procedures to improve the credibility of causal claims based on qualitative research. This is a bold book that calls on qualitative researchers to go beyond current thinking about process tracing and makes a major contribution to qualitative methodology.' Gerardo L. Munck, Professor of Political Science and International Relations, University of Southern California