The realist approach is gaining popularity among social scientists, especially among those whose research objects are complex, such as programs, projects and public policies that seek to improve a social situation. Indeed, the realist approach has been adapted to the practice of program evaluation, and more recently of systematic review. Research methods rooted in critical realism seem better adapted to the demands of the movement for evidence-based decision- and policy-making. However, the realist approach is still rarely known and used, especially among francophone evaluation researchers and students. The first objective of this article is thus to introduce in a didactic way the epistemological foundations and key concepts of the realist approach to program evaluation and systematic review. The second objective is to illustrate, through a case study of a realistic review, the conceptual and methodological learning about the practice of realistic evaluation. This reflexive approach is part of a movement of sharing knowledge and best practices on the realist approach.