Training helps maintain high-quality supervision and its associated benefits (e.g. reduced burnout, improved care). While studies have previously evaluated extended-duration supervision training programmes, none have treated these as complex interventions so have not employed realist approaches.

Building on a previous realist synthesis, this evaluation tests and develops programme theory for extended-duration supervision training to answer the question: to what extent does the supervision training programme work, for whom, under what circumstances and why?

We conducted a realist evaluation of a novel state-wide Victorian 3-month supervision training programme including one or two 3.5-h workshops followed by weekly reflexive longitudinal audio diaries (LADs) for up to 12 weeks.

Realist evaluation data comprised 25 entrance interviews with nurses and allied health professionals, 176 LADs (and 29 written diaries), and 23 exit interviews. We employed team-based realist analysis to identify context-mechanism-outcome configurations (CMOCs) to test and develop programme theory.

We refined four recurring CMOCs from the realist synthesis programme theory, found insufficient evidence for two, and established five new recurring CMOCs. We identified multiple positive outcomes from our extended-duration supervision training programme (e.g. improved supervisor practices) through various mechanisms relating to pedagogy (e.g. weekly reflexivity), supervisors (e.g. engagement), and workplaces (e.g. enabling supervision cultures). Some negative outcomes were reported (e.g. decreased engagement) through various mechanisms (e.g. suboptimal training design). Such mechanisms were thought to come about by diverse contexts including supervisors (e.g. inexperienced/experienced), professions (nursing/allied health), and organisations (supervision-enabled/non-enabled cultures).

Our findings extend the realist synthesis programme theory by highlighting various contexts triggering outcome-generating mechanisms. Programme outcomes are maximised through ongoing supervisor reflexivity paying attention to facilitator-supervisor relationships, as well as protected time for supervisors to translate learning into practice.