Social perspective taking (SPT; i.e., the social-cognitive process of inferring another person’s thoughts and feelings) is commonly thought to be essential for successful social relationships, yet the bulk of past work on the development of SPT does not consider youths’ tendency to engage in SPT in the context of their close relationships. The current study of adolescents (ages 12–17, N = 158) helps move the field forward by distinguishing between adolescents’ SPT ability (i.e., whether they are developmentally capable of SPT) and their tendency to apply this ability in their actual social relationships, namely, friendships, and considering the roles of gender and age. Results indicate that SPT ability and SPT tendency are distinct, suggesting that youths do not always put to use the SPT skills that they possess. Girls scored higher than boys on both SPT ability and SPT tendency. Boys and girls had significant gains in SPT ability across adolescence. Surprisingly, however, boys’ SPT tendency decreased from early to later adolescence, indicating that older boys tend to engage in less SPT in their friendships despite increasing ability to do so. This is worrisome given the importance of SPT in promoting high-quality relationships. Importantly, gender role ideology predicted this tendency in boys, such that boys with more stereotypical gender beliefs tended to engage in less SPT with their friends. Thus, the current findings point to the importance of going beyond mean-level gender differences to consider gendered beliefs and suggest that interventions aimed at promoting egalitarian views may help foster SPT and successful friendships among boys.