Using an observational methodology to examine sibling communication, sisters (N = 28 dyads) were videotaped discussing their ideas about dating and sexuality. Social provision theory was used as a framework for the examination of roles enacted by sisters during these conversations. Inductive thematic analytic procedures were conducted, and three roles were identified: sisters as confidants, sources of support, and mentors. Older and younger sisters served as confidants and sources of support for one another, whereas older sisters were more likely to be mentors for their younger sisters than vice versa. Findings indicate the potential importance of sisters in the formation of adolescent girls' ideas about romantic relationships and sexuality, sibling communication as a socialization mechanism of sisters' similarities in romantic experiences and sexual behaviors/attitudes, and the inclusion of older sisters in prevention intervention programs focused on reducing adolescent sexual risk behaviors and promoting healthy romantic relationships and sexuality development.