Knowledge transfer between age-diverse employees is gaining importance because of demographic change. We took a relational perspective to examine the indirect effect of human resource practices on knowledge transfer through age-diversity climate in age-diverse coworker dyads and contextualised our model by testing country difference and dyadic age difference as moderators. We used data from 159 age-diverse coworker dyads from China and Germany to test our hypotheses. We found that perceived age-inclusive human resource practices were positively associated with knowledge sharing and receiving through age-diversity climate. However, we did not find support for our hypothesis that these indirect effects differed when comparing China and Germany as examples of collectivist and individualist countries. Furthermore, we did not identify the proposed moderating effects of dyadic age difference as the indirect effects of age-inclusive human resource practices were not significantly different for age-diverse coworker dyads in which dyadic age difference was high (vs. low).