This paper examines an increasingly used methodology developed by Pawson and Tilley [1] that they termed, ‘Realistic Evaluation’. The paper provides an overview of methodology as well as exploring its underpinning philosophy, that of critical realism. The paper suggests that Realistic Evaluation provides a useful means of exploring the health and social sciences through the use of mixed methods and concludes with how a researcher might go about constructing a Realist Evaluation study.