Derek Beach and Rasmus Brun Pedersen introduce a refined definition of process tracing, differentiating it into three distinct variants and explaining the applications for and limitations of each. The authors develop the underlying logic of process tracing, including how one should understand causal mechanisms and how Bayesian logic enables strong within-case inferences. They provide instructions for identifying the variant of process tracing most appropriate for the research question at hand and a set of guidelines for each stage of the research process.