Amid growing recognition that strong academic skills alone are not enough for young people to become successful adults, this comprehensive report offers wide-ranging evidence to show what young people need to develop from preschool to young adulthood to succeed in college and career, have healthy relationships, be engaged citizens, and make wise choices. It concludes that rich experiences combining action and reflection help children develop a set of critical skills, attitudes, and behaviors. And it suggests that policies should aim to ensure that all children have consistent, supportive relationships and an abundance of these developmental experiences through activities inside and outside of school.