Realist evaluation aims to explain the processes involved in introducing an intervention in a particular context (with certain characteristics and groups of actors operating within it), and the outcomes observed after the intervention implementation. It is particularly relevant to evaluations involving human services, social policies, health interventions and more.

Realist evaluation has gained prominence in the field of evaluation in recent years. Its theory-driven approach to explaining how and why programmes work or not makes it attractive to many novices, early career researchers, and organisations implementing various programmes globally and relevant to policymakers and programme implementers. While realist evaluation seeks to be pragmatic, adopting principles and methods that can be used to help focus an evaluation, its deep ontological and epistemological foundations make its application in real-life situations challenging.

In this paper the authors seek to unpack the key tenets scaffolding the practical application of realist evaluation and argue that an amalgam of scientific and critical realist principles underpins realist evaluation. These principles are unpacked to illustrate how they fit into each other to provide a cogent theoretical foundation for realist evaluation.