Introduction: Mechanisms and process tracing

There has always been a close association between the empirical method of process tracing and a theoretical interest in causal mechanisms. In their highly influential 2005 book on case-study research, Alexander George and Andrew Bennett refer to process tracing as “an operational procedure for attempting to identify and verify the observable within-case implications of causal mechanisms.” It would probably be fair to say that most methodologists and practitioners of process tracing see the approach largely in these terms: as the search for evidence of the mechanisms that are operating within a case and that generated or contributed to the outcome of interest.