In the United States, student social-emotional well-being has become a priority because of concerning mental health and well-being outcomes for adolescent youth. High schools and school districts have responded by expanding mental health and social-emotional supports. However, there is little research to understand the ways in which educational leaders--including superintendents, school district coordinators, and principals--organize practices and policies to support social-emotional well-being for high school students. In this report, the authors seek to close this research gap by presenting findings from a multi-method, multiyear national study on social-emotional well-being initiatives, focusing on high school students. The authors' takeaways include insights about high school staffing, high school--specific practices that support social-emotional well-being, district-level supports, equity-oriented social-emotional well-being supports for minoritized students, and challenges to implementing or maintaining social-emotional well-being initiatives at the high school level. The authors also provide recommendations aimed at school district leaders, high school leaders, and educational policymakers.