Table 1.

Realist glossary of terms

Term	Definition
Realist theory	A theory which makes reference to the underlying generative mechanisms that exist in the domain of the real.126
Realist review	The process of evidence review that follows the realist approach.127
Context	Any condition that triggers and/or modifies the behaviour of a mechanism.128
Mechanism	Underlying entities, processes or structures which operate in particular contexts to generate outcomes of interest. Mechanisms are causal, hidden, context sensitive and generate outcomes.129
Outcome	The impact resulting from an interaction between mechanisms and contexts.123 Intended or unintended outcomes triggered by a mechanism within a given context. These may be proximal (immediate) or distal (future).
Programme theory	The ideas and assumptions underlying how, why and in what circumstances complex social interventions work.35 An abstracted description and/or diagram that lays out what a programme/family of programmes comprises and how it is expected to work.130 Programme theory explains the sequence of implementation of an intervention and provides theories of change to explain how outcomes are generated by mechanisms. It is thus a theory of causation and implementation.
Context-mechanism-outcome configuration	A statement that describes the relationship between context, mechanism and outcome, such that a context triggers a mechanism, which then produces an outcome.128