Research and practice in medical decision making value consistency with standardized intervention, potentially neglecting the impact of various environmental features such as workload or the constraints of local work practice. This study presents both qualitative and quantitative analyses of emergency physicians’ decision-making processes in their natural work setting to examine the impact of contextual features. We study contextual effects on two separable decision-making processes identified in quantified observational data: goal enactment and goal establishment. Whereas goal enactment responds to hospital differences and patient difficulty as main effects, goal establishment responds to their interaction. Our emphasis on goal establishment expands the scope of a medical decision-making literature focused on diagnosis, and extends to other professions and the more general conceptualization of expertise. From a theoretical perspective, we emphasize the importance of accounting for contextual variability within the bounds of expert behavior. Practically, we provide real-world examples of context effects that bear on the standardization of care, cost differences between hospitals, and the conceptualization of quality medical care.