In 1999, GLSEN identified that little was known about the school experiences of lesbian, gay, bisexual, and transgender (LGBT) youth and that LGBT youth were nearly absent from national studies of adolescents. We responded to this national need for data by launching the first National School Climate survey, and we continue to meet this continued need for current data by conducting the study every two years. Since then, the biennial National School Climate Survey has documented the unique challenges LGBT students face and identified interventions that can improve school climate. The survey documents the prevalence of anti-LGBT language and victimization, such as experiences of harassment and assault in school. In addition, the survey examines school policies and practices that may contribute to negative experiences for LGBT students and make them feel as if they are not valued by their school communities. The survey also explores the effects that a hostile school climate may have on LGBT students’ educational outcomes and well-being. Finally, the survey reports on the availability and the utility of LGBT-related school resources and supports that may offset the negative effects of a hostile school climate and promote a positive learning experience.