This chapter makes the conceptual and empirical case for using acceptance and commitment therapy (ACT) with youth in school settings. We provide background for this project by making a logical, evidence-based case for school-based mental health services more generally. We then outline a public health approach to using ACT in schools via multitiered system of supports (MTSS), which emphasizes scaled prevention at universal, targeted, and intensive levels. Following, we review the existing literature on ACT in schools—concluding there is adequate evidence to support use at the targeted level, encouraging yet weaker evidence supporting use at the universal level, and promising yet extremely limited evidence for use at the intensive level. We close the chapter by discussing the limitations and challenges of using ACT in schools, offering future directions for progressing research and practice. We suggest future work in this area might especially benefit from (a) enhancing the methodological rigor of research designs in school-based studies, (b) testing the viability of brief or focused ACT at the targeted level in schools, (c) investigating the treatment utility of ACT-related process measures in schools, and (d) expanding the scope of ACT in schools to promote the wellbeing of teachers and other educators.