Scholars have differentiated other-oriented (OO) purpose (i.e., a personally meaningful life aim intended to contribute to the world beyond the self) and self-oriented (SO) purpose (i.e., a personally meaningful life aim without intention to contribute beyond the self). OO purpose is associated with adolescent thriving, yet little is known about how to cultivate it. In a study of 207 adolescent girls, we examined how positive parent--adolescent relationships may contribute to developing OO versus SO purpose; we also tested whether the association between parent--adolescent relationships and OO purpose was mediated by prosocial behavior.