A model of organizational characteristics, occupational stress and mental health in emergency medical technicians (EMTs) is developed and tested. Supervisor behavior and work group support are used as predictors of negative role perception. Negative role perception is specified as intervening between the organizational variables and occupational stress. Occupational stress is hypothesized to directly influence depression. Data collected from 250 EMTs is used in a structural equation analysis to estimate model parameters. The sample is mostly male (74%), white (94%), and married (68%). Results suggest that there is a direct relationship between perceived occupational stress and increased depression. Role perception is a critical intervening variable between supervisor behavior, work group support, and occupational stress. The findings suggest that EMTs are more satisfied when supervisory practices result in an environment which encourages open expression and group problem solving. This work environment leads to more supportive relationships among squad members, reduced role ambiguity, and decreased occupational stress and depression.