Social scientists have identified a need to move beyond the analysis of correlation among variables to the study of causal mechanisms that link them. Nicholas Weller and Jeb Barnes propose that a solution lies in 'pathway analysis': the use of case studies to explore the causal links between related variables. This book focuses on how the small-N component of multi-method research can meaningfully contribute and add value to the study of causal mechanisms. The authors present both an extended rationale for the unique role that case studies can play in causal mechanism research, and a detailed view of the types of knowledge that case studies should try to generate and how to leverage existing large-N data to guide the case selection process. The authors explain how to use their approach both to select cases and to provide context on previously studied cases.