Background: Medical students and residents are expected to be able to manage a variety of critical events after training, but many of these individuals have limited clinical experiences in the diagnosis and treatment of these conditions. Life-sized mannequins that model critical events can be used to evaluate the skills required to manage and treat acute medical conditions. The purpose of this study was to develop and test simulation exercises and associated scoring methods that could be used to evaluate the acute care skills of final-year medical students and first-year residents. Methods: The authors developed and tested 10 simulated acute care situations that clinical faculty at a major medical school expects graduating physicians to be able to recognize and treat at the conclusion of training. Forty medical students and residents participated in the evaluation of the exercises. Four faculty members scored the students/residents. Results: The reliability of the simulation scores was moderate and was most strongly influenced by the choice and number of simulated encounters. The validity of the simulation scores was supported through comparisons of students'/residents' performances in relation to their clinical backgrounds and experience. Conclusion: Acute care skills can be validly and reliably measured using a simulation technology. However, multiple simulated encounters, covering a broad domain, are needed to effectively and accurately estimate student/resident abilities in acute care settings.