BACKGROUND: Confusion remains about the use of the observer role in simulation. Observational learning is an emerging form of brain-based learning that is applicable to experiential learning and simulation, warranting the further exploration of theoretical foundations. This article describes how observational experiential learning theoretically supports the use of observer roles in simulation. METHOD: Constructs and concepts from experiential learning and observational learning theories were explored in tandem with brain-based learning evidence from different disciplines. RESULTS: Observational experiential learning was developed by merging these theories together in simulation and debriefing to support both observer and participant roles for learning outcomes. CONCLUSION: Observational experiential learning incorporates experiential learning, social learning, and social cognitive theories to support the use of the observer role. Educators should consider strategies to foster attention and motivation through prebriefing, debriefing, and observational brain-based learning protocols. [J Nurs Educ. 2020;59(1):7-14.].