This action guide was designed for school administrators in kindergarten through 12th grade schools (K-12), including principals and leaders of school-based student support teams, to identify evidence-based strategies, approaches, and practices that can positively influence students' mental health. This action guide describes six in-school strategies that broadly promote and support mental health and well-being. The strategies in this guide are not intended to replace the individual behavioral and mental health treatment services that are critical to the children and young people who need them. For each strategy in this action guide, approaches or specific ways to use the strategy are provided, and a summary of evidence-based policies, programs, and practices that illustrate each approach is included. Tips to support successful and equitable implementation of strategies are described, with considerations for how to ensure all students are benefitting from mental health promotion and well-being efforts.