Multidimensional, competency-based instruments appear to provide a robust view of IPE teamwork; however, challenges remain. Due to the large scale of the simulation exercise, observation-based assessment did not function as well as self- and standardized patient-based assessment. To promote greater variation in observer assessments during future Disaster Day simulations, we plan to adjust the rating scale from "not observed," "observed," and "not applicable" to a 4-point scale and reexamine interrater reliability.