School based mental health interventions provide a promising treatment pathway for a variety of mental health concerns. They can be provided on a wide scale to students with a variety of presenting concerns, and allow access to needed services where barriers may otherwise prevent treatment. A majority of the existing literature on this topic has focused on elementary-aged populations; however, there is a need to identify effective treatments for older students. Adolescents experience risk factors and psychiatric needs distinct from those of younger children. Accordingly, treatments for younger students may not generalize to adolescents, and it is imperative to identify effective interventions to support this population. While previous research has included adolescents as part of a larger sample, to date there have been no meta-analyses examining the broad impacts of school based mental health interventions specifically among an adolescent population. The present study conducted a meta-analysis in order to synthesize the results of existing literature on school based mental health interventions for secondary students. The aims of the study were to identify the overall impact of these interventions on adolescent mental health outcomes and to identify specific moderators that impact the effectiveness of interventions. Moderators examined included broad and narrow target outcomes (e.g., internalizing symptoms, externalizing symptoms, and substance use), intervention modality (e.g., cognitive behavioral, mindfulness-based, etc.), intervention provider (e.g., mental health professional, teacher, computer, etc.), intervention level (e.g., universal, targeted, or individual), and select student characteristics (e.g., status as a racial/ethnic minority or English learner). Results of this study revealed small overall improvements in adolescent mental health. Examining results based on moderators of interest yielded some larger effects. Intervention level predicted student outcomes, with individual and targeted services leading to greater improvements than interventions delivered universally. Interventions delivered by mental health professionals led to greater improvements than interventions delivered by teachers. Additionally, studies with individual-level interventions addressing internalizing symptoms, studies targeting trauma symptoms, and studies including a high proportion of English learners produced medium to large improvements. Future research should examine additional moderators that may influence adolescent response to intervention such as dose, specific intervention protocol, and additional student characteristics. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]