Process tracing is a theory-based method uniquely suited to assessing an intervention’s contribution to outcomes, especially for interventions that are difficult to quantify, such as knowledge work or institution building. Because it relies on iteratively developing and empirically testing granular theories of change with a focus on processes, process tracing enhances the ability of evaluators to establish strong causal links between interventions and outcomes. Furthermore, process tracing emphasizes the explicit connections between actors, their actions, and resulting behavioral changes, offering two key advantages to evaluators. First, it provides a transparent framework for presenting and evaluating the strength of the evidence gathered. Second, it enables evaluators to derive practical lessons more easily.

The robustness of process-tracing findings, however, critically depends on how well theory and empirical observables come together. This paper explores the potential of process tracing in evaluation, providing a step-by-step guide for its implementation and discussing its advantages and limitations through an examination of a recent application of the method in an Independent Evaluation Group evaluation. The case examines the impact of the World Bank’s knowledge and policy work in a middle-income country. Although the World Bank’s impact comes as much from data, analytics, and advisory services as it does from the financing it provides, impacts from the former tend to be understudied and underevaluated, in part because of the lack of awareness of, and use of, process tracing and other methods.