Research on adolescents has taken great strides to acknowledge and celebrate the assets that young people have and can develop in and out of school. Queer youth, however, are often left out of these conversations, as researchers focus on their damage. This dissertation incorporates LGBTQ+ youth into the scientific discourse of youth’s assets, especially those that are associated with healthy development in school: supportive relationships with non-parental adults, strong relationships with peers, supportive school climate, and participation in after-school activities. First, this dissertation explores the relative strength of these assets, as well as other student- and school-level factors, in predicting students’ sense of school belonging using multilevel structural equation modeling with data from 2,464 students at 19 schools. Then, the dissertation focuses on one specific asset: participation in after-school activities. Drawing on qualitative, semi-structured interviews with 44 students, this dissertation works to better understand students’ reasons for joining their Gender and Sexuality Alliances (GSAs). Finally, the dissertation explores predictors of students’ engagement in and leadership of their GSAs, employing multilevel structural equation modeling with data from 179 youth at 17 schools. This work clearly identifies queer youth’s assets, rather than solely or primarily focusing on their deficits, and works to understand the ways in which these factors combine to predict school belonging. Additionally, it provides insight into the motivations students offer for joining their GSAs, encouraging youth to see themselves as agentive forces capable of making needs claims and informing researchers and practitioners about what they desire from the GSA, as well as what skills they bring to it. Finally, this dissertation explores factors that are associated with students’ engagement in and leadership of GSAs, drawing on research that indicates that engagement may be the fundamental component that links after-school participation and a host of positive outcomes. Taken as a whole, this dissertation illuminates queer youth’s assets and needs, offering researchers and practitioners insight into fostering supportive school environments, creating spaces for queer youth to flourish, and meeting queer youth’s needs while still acknowledging their strengths.