Previous research focused on sexual prejudice has shown that lesbian and gay adolescents are at greater risk of peer harassment and victimization than their straight counterparts. Peer victimization such as exclusion, however, may also be related to conventional expectations adolescents hold about their social environment. This study examined adolescents' (N = 1069) attitudes and reasoning about the exclusion of peers based on sexual orientation and gender nonconformity. Results indicate that although participants reported it was more acceptable to exclude their gay or lesbian, as opposed to straight, peers, gender nonconformity was also a distinguishing factor. Whereas mannerism and activity nonconforming gay targets were rated less positively than similarly nonconforming straight targets, straight appearance nonconforming targets were not evaluated differently than gay appearance nonconforming targets. Further, the types of reasoning adolescents used to justify their exclusion judgments varied by sexual orientation and gender nonconformity of the target.