The report first documents the fact that school-age children and teens who are unsupervised during after-school hours are far more likely to use alcohol, drugs, and tobacco; engage in criminal and other high-risk behaviors; receive poor grades; and drop out of school, compared to children who participate in constructive after-school activities supervised by responsible adults. The after-school activities profiled in this report were selected because they have shown evidence of success, whether empirical or anecdotal, and were identified by local, regional, and national experts as particularly innovative or promising. They encompass educational and recreational programs, homework help, music lessons, sports activities, workshops on conflict resolution and alcohol and drug prevention, and character-building activities. A chapter on the components of exemplary after-school programs focuses on goal setting and strong management; staffing; safety, health, and nutrition issues; partnerships with community-based organizations, juvenile justice agencies, law enforcement, and youth groups; family involvement; coordinated learning with schools; linkages between school and after-school personnel; and evaluation of program progress and effectiveness. Listings of resources and publications are provided.