Process tracing is an in-depth case study method that can be used to study how causal processes play out within cases. Given its focus on processes and temporality, process tracing is a useful method for analyzing crisis and crisis decision making in the fields of foreign policy analysis and public policy. As can be seen from its name, process tracing involves theorizing a causal process that is then traced by investigating the observable manifestations of the operation of the process as a whole in the more minimalist variant, or for each of its parts in the more maximalist variant. Minimalist process tracing is typically used early in a research program as a form of plausibility probe to understand what types of processes might be linking a crisis event with particular outcomes like policy change. Maximalist process tracing can then be used once there is preliminary knowledge about processes, and where the goals become gaining a better theoretical understanding of how they operate, and making stronger causal inferences using more direct evidence of their operation.