Gender is an important social category that affects adolescents' lives in multiple ways. Gender identities and gender schemas shape the kinds of ideas and behaviors that adolescents may consider appropriate for themselves and others. Stereotyped beliefs may lead to sexism, including prejudiced attitudes and discriminatory behaviors. Gender-related variations during adolescence occur in academic achievement, athletic participation, sexuality, body image, dating relationships, friendship intimacy, and aggression. © 2011 Elsevier Inc. All rights reserved.