What motivates individuals to engage in role-incongruent knowledge transfer? Drawing on role congruity theory, we characterize role-incongruent (“reverse”) knowledge transfer as being based on an incongruity of the functional and social roles of the actors. Further integrating status characteristics theory and relational demography, we propose affect- and cognition-based trust as well as age as determinants of individuals’ engaging in such reverse knowledge transfer. In so doing, we distinguish between the social roles of trainers and apprentices, as these social roles carry implications for which behaviors are regarded as role-congruent or -incongruent. We test the resulting conceptual framework based on individual-level data from 442 participants (338 apprentices and 104 trainers) in multiple organizations within the context of vocational education training. The results largely support our hypotheses: For trainers, affect-based trust in apprentices and own age are positively associated with role-incongruent knowledge seeking, and the latter relationship is positively moderated by apprentice age. For apprentices, affect based trust is positively and cognition-based trust is negatively related to their role-incongruent knowledge sharing, but age has no significant effect. Finally, supplementary analyses document that the antecedents of reverse knowledge transfer differ from those factors that are significantly related to role-congruent knowledge exchange.