International clinical practice guidelines for the management of psychological trauma recommend Psychological First Aid (PFA) as an early intervention for survivors of potentially traumatic events. These recommendations are consensus-based, and there is little published evidence assessing the effectiveness of PFA. This is not surprising given the nature of the intervention and the complicating factors involved in any evaluation of PFA. There is, nevertheless, an urgent need for stronger evidence evaluating its effectiveness. The current paper posits that the implementation and evaluation of PFA within high risk organizational settings is an ideal place to start. The paper provides a framework for a phasic approach to implementing PFA within such settings and presents a model for evaluating its effectiveness using a logic- or theory-based approach which considers both pre-event and post-event factors. Phases 1 and 2 of the PFA model are pre-event actions, and phases 3 and 4 are post-event actions. It is hoped that by using the Phased PFA model and evaluation method proposed in this paper, future researchers will begin to undertake the important task of building the evidence about the most effective approach to providing PFA in high risk organizational and community disaster settings.