Evidence in psychology and economics has converged on an understanding of what matters for students' learning and what influences their life trajectories. While earlier work focused on the role of large scale assessment test scores, more recent research emphasizes the importance of socioemotional skills, experiences, and mindsets--such as conflict resolution, conscientiousness, goal-setting, study skills, belonging, and adaptive self-beliefs--for thriving in adolescence and into adulthood. This updated scientific knowledge about socioemotional factors has mobilized action in educational policy. This report examines on what schools can do well to positively affect students' long-term trajectories. The findings show the value of taking a holistic view of adolescents, and that fostering students' engagement and a challenging, supportive environment for them are the most important things schools can do. The findings and interpretive summary offer insights on some of the most-discussed K-12 policies and practices today, including test scores, school quality metrics, school climate, and student voice.