The Afterschool Alliance's recent examination of multiple studies of after-school program impact found solid evidence that:

• After-school programs keep children and youth safe and protect them from negative and unsafe behaviors.

• After school programs help working parents.

After-school activities help youth develop social skills, improve academic performance, and help them build strong supportive relationships with adults other than their parents. Young children benefit especially from the social skills development and improved academic skills. This leads to improved conflict management and better school attendance. Middle-school aged youth who continue to participate in after-school activities are more likely to be engaged in school and attentive in class and less likely to be involved in violent behavior at school.
Participation in after-school activities continues to be a benefit for students right through high school. Adolescents in after-school programs are optimistic for the future and have more interest in school than peers who are unsupervised after school. After-school program participation also helps to keep youth from skipping school and experimenting with alcohol, drugs and sexual activity. In fact, the 1995 Westat, Inc. analysis of national data found that students who spend no time in after-school activities are 49 percent more likely to have used drugs and 37 percent more likely to become teen parents than students who spend one to four hours per week in after-school activities.
Excerpt from:

•  http://www.ext.colostate.edu/PUBS/columncc/cc060905.html