A debate has arisen out of the need to understand true intervention outcomes in the social sciences. Traditionally, the randomized, controlled trial that answers the question of ‘what works’ has been considered the gold standard. Although randomized, controlled trials have been favoured in organizational intervention research, there has been an increasing interest in understanding the influence of context and intervention processes on the outcomes of such interventions. In the present critical essay, we question the suitability of trials and meta-analyses to evaluate the effectiveness of organizational interventions and we suggest that realist evaluation that seeks to answer the questions of what works for whom in which circumstances may present a more suitable framework. We argue that examining the content and process mechanisms through which organizational interventions are effective, and the conditions under which these are triggered, will enable us to better understand how interventions achieve the desired outcomes of improved employee health and well-being. We suggest that organizational intervention content and process mechanisms may help bring about the desired outcomes of improved employee health and well-being and that contextual factors determine whether these mechanisms are triggered.