Adolescents spend more time in school than in any other context and substantial research suggests that feeling connected to one's school during adolescence promotes concurrent and long-term positive youth development. Yet, by high school as many as 40-60% of all youth are disengaged from school, placing them at risk for maladaptive development both in adolescence and into adulthood. This article reviews the research literature on school connectedness, focusing on implications for youth development; predictors of school connectedness; and the importance of school connectedness as a focus of prevention.