Introduction: Physician burnout is considered an epidemic. In 2019, 44% of U.S. physicians reported feeling burned out. The work environment is a central risk factor for this. The aim of this study is to develop and test an instrument to evaluate work environment factors in medical training courses. Method: After focus groups, an initial pool of 14 items was generated and tested in a pilot study (n = 66). Face validity was verified, and small adjustments were made. The resulting version was administered to a sample of 115 psychiatry residents. Eleven items were selected based on the correlations between them, principal component analysis, and theoretical reasons, and then tested for internal and construct validity. Results: The final version had high reliability (Cronbach’s alpha = 0.898) and comprised three dimensions: relations with the institution; with colleagues; and with preceptors. Both total scores and dimensions correlated significantly with burnout scores (p < 0.01). Cutoffs defining the environment as healthy (>32 points); risky (23-31 points); or toxic (<22 points) were suggested and related to the risk of burnout. Conclusion: Several authors have emphasized the importance of approaching institutional factors as an effective strategy for coping with the increased prevalence of burnout. This instrument should contribute to these efforts.