This study examined the relations between school climate and school adjustment among 101 lesbian, gay, and bisexual (LGB) high school students and the moderating influence of social support on those relations. Students completed surveys to assess three aspects of the school climate (the school's exclusion/inclusion of LGB people, personal victimization in school for being LGB, and social support from teachers) as well as social support from family and close friends. Criterion variables were GPA, school belonging, and discipline problems. School climate variables explained significant amounts of variance in all criterion variables, after controlling for prior GPA, and there were no moderating effects of parent or friend support. Cluster analyses revealed one small group (n = 14) of highly vulnerable youth who were the least adjusted, most victimized, and least supported. Implications for teachers, counselors, and future research are discussed. (Contains 4 tables.)