Abstract Measures of appraisal, situational stressor, and locus of control were administered to first- and second-year medical students ( n = 433). Based on a cognitive-phenomenological model of stress, it was hypothesized that appraisals of threat/challenge and change/accept would be related to locus of control differentially depending on the type of stressor or situation appraised. Three types of stressors were examined related to the academic environment, social/familial issues, and personal performance. Internals and externals did not differ in their appraisal of social stressors. Internals, compared with externals, perceived less threat and more mutability when appraising personal performance stressors. In contrast, when appraising stressors in the academic environment internals actually perceived less mutability than externals. More importantly, however, internals accepted academic stressors perceived to be unchangeable, whereas externals did not. The observed I-E/situational stressor interactions were in line with expectations from existing theory. The fact that appraisal was better predicted by the interaction of person and situation factors rather than by either factor alone lends support to a cognitive-phenomenological model of stress.