We are in the midst of a youth mental health crisis. Yet, many children and adolescents who need services do not have access to high-quality mental health care. This is especially true for low-income and economically marginalized families and youth of color. Schools offer an ideal setting in which children and adolescents can access services; however, limited resources (e.g., time and training) are frequently cited barriers to providing school-based mental health care. Single-session interventions (SSI; i.e., one-time psychologically and therapeutically based interventions designed to quickly address mental health issues) have the potential to increase access to high-quality school-based mental health services for children and adolescents. Therefore, the purpose of this literature review was to explore the evidence base of single-session interventions for youth to identify brief, empirically supported, and accessible mental health interventions that school psychologists could deliver in schools. Specifically, this review examines the evidence base for several single-session interventions designed for use with various clinical and nonclinical youth populations and concludes with a brief discussion of future directions for SSI research and practice in school psychology, including the use of SSIs in school settings to increase access to high-quality mental health care for children and adolescents that may otherwise not receive care.