Organizational interventions are often recommended when organizations want to improve employee psychological health and well-being. Research, however, has revealed inconsistent results and reviewers have called for research on why interventions either bring about desired change or fail to do so. Answering the “how” and “why” of intervention outcomes requires a close examination of the elements that hinder or facilitate desired outcomes, thus moving beyond evaluation of only the overall effects. In this paper, we present an evaluation framework based on recent intervention research and process-oriented organization theory. The framework offers suggestions for which elements to include when evaluating organizational interventions. Within the framework, elements crucial to intervention evaluation are grouped into four overarching categories that we argue are crucial to evaluation over the five phases of an intervention programme. These categories are: the organizational “actors”; the mental models of those actors; the context of the intervention; and intervention design and process. Evaluation during the process as well as of the overall effects, as recommended by this framework, should throw light on what works for whom, why, how and under which circumstances.