Recent research into imposter phenomenon, or internal feelings of questioning competence, has shifted away from conceptualizing the feeling as an individual characteristic that requires an individual solution toward instead examining the role of context. We used a 2 (Generational Status: First Generation vs. Continuing Generation) × 3 (Environment: Classroom vs. Peer vs. Administration) × 2 (Social Comparison: Present vs. Absent) experimental vignette design. Overall, we found that, for both first- and continuing-generation students, social comparison messages differentially impacted imposter feelings depending on context, with the most elevated levels in social comparison messages from administrators and peers. Findings contribute to a better understanding of structural conditions that exacerbate or lessen imposter feelings at highly selective post-secondary institutions.