This chapter describes the types and prevalence of social, emotional, and behavioral (SEB) problems that school-age youth may experience. It describes how these problems affect students in educational settings. The chapter presents a multi-tiered model of service delivery, including intervention and assessment strategies, for supporting students’ SEB wellness in schools. Within a multi-tiered ... [Show full abstract] framework, school psychologists and other personnel can provide high-quality, evidence-based supports that are appropriately matched to the type and intensity of students’ needs. Multi-tiered systems of support (MTSS) allow schools to make the most efficient use of their potentially limited mental health and behavioral support resources. This chapter surveys a variety of common assessment and intervention methods at each tier. The literature on school-based SEB assessment and intervention is expansive, and practitioners should be well versed in this research before selecting procedures for their unique school contexts.