Based on the social cognitive theory and the emotional contagion theory, this study investigated if friends influence (reinforce or change) the development of academic values (intrinsic value, emotional cost) and if this process differs across same-sex friendship dyads. We drew on data collected in a two-wave longitudinal study in Germany. The final sample was based on 264 stable reciprocated friendship dyads of grades 5 and 7 (148 female dyads and 116 male dyads). Results of actor-partner-interdependence models indicated that friends reinforce each other regarding the intrinsic value and initiate change regarding the emotional cost. Moreover, female and male friendship dyads did not differ in the strength of influence on academic values. Results were discussed in terms of selection and socialization effects regarding friendships.