This study examined whether older siblings influence early adolescent girls' sexual socialization. Participants were 180 girls, 12 to 14 years old, from predominantly ethnic minority backgrounds. They completed a battery of interviewer‐administered measures assessing a range of sexual cognitions and romantic and sexual behaviors. As predicted, compared with other girls, girls with older brothers placed greater value on becoming a parent, had lower levels of sexual responsivity or interest, and reported smaller age discrepancies between themselves and their partners for their first romantic kiss. Regardless of sibling sex, having older siblings was associated with more restrictive sexual cognitions and behaviors. Findings are interpreted in the context of sexual script theory.