Background: Therapeutic communities (TCs) are becoming increasingly widespread as a form of treatment for entrenched mental health problems, particularly addictions and personality disorders, and are equally used in educational, prison and learning disability settings. Despite growing evidence for their effectiveness, little research has been conducted to establish how TCs work to produce positive outcomes. We hypothesize that there are two specific factors that in combination contribute to TC effectiveness: the promotion of a sense of belongingness and the capacity for responsible agency. Although both factors are found in other therapeutic approaches and are important to the psychosocial aspects of psychiatric care more generally, we argue that their combination, extent and emphasis are unique to TCs.

Material: Drawing on social and experimental psychology, we: (1) review research on a sense of belongingness and the capacity for responsible agency; (2) establish the mechanisms by which TCs appear to promote them; (3) draw lessons for TC practice; and (4) suggest why they may contribute to positive outcome.

Discussion: A sense of belongingness is correlated with improved self-esteem and overall well-being. The capacity for responsible agency is central to behavioural change. TCs are typically used in fields where positive outcome requires both personal growth and behavioural change. We suggest that TCs are uniquely placed to demand such growth and change of their members because the sense of belongingness engendered by TC methods protects against the risks engendered by this demand.

Conclusion: Empirically informed, evidence-driven research is necessary to understand how TCs work and how TC practice can be improved. This understanding may offer lessons for the improvement of psychosocial aspects of psychiatric care more generally.