Experiences that are deeply engaging and enjoyable, engender full concentration, and present a balance between challenge and skill propel or push development forward. For the past twenty years, researchers have sought to locate environments in which this combination of effort, skill, interest, and enjoyment is more likely. This article describes a research study conducted by the authors focusing on the experiences of ethnically and economically diverse youth who attended after-school programs. These youth resided in three states and attended eight different middle schools. Some of the youth, whom they called "program youth," participated in school-based after-school programs during at least part of the after-school hours. Others, whom they called "nonprogram youth," did not. The authors concluded from their analyses that school-based after-school programs provide youth with substantially different opportunities and experiences than they would otherwise have. Youth spend more time doing sports, art and academic enrichment, community service, and homework at programs versus elsewhere. They devote less of their after-school hours to watching TV and eating. While engaging in these activities at programs, they experience more intrinsic motivation, put forth more concerted effort, and feel less apathetic, underscoring the potential of after-school programs as a positive developmental context. (Contains 2 tables and 8 notes.)