The Institute of Museum and Library Services (IMLS) helps museums and libraries preserve our cultural heritage, enhance learning and innovation, and develop staff capacities to provide the best in service to our communities. IMLS has a long-standing commitment to funding grants and sponsoring research on the subject of how both preschool and school-age children learn, and how museums and libraries support such learning. This report shares the results of a year-long study of the impact of IMLS grants (1998-2003) through programs that served youth aged 9-19. Nearly 400 museum and library programs were surveyed about their goals, strategies, content, audience, and structure, as well as about their impact, effectiveness, and outcomes. Perhaps the most important finding is that everyone benefits when museums and libraries apply positive youth development (PYD) principles and partner with other organizations that serve youth. The report makes three recommendations: (1) The museum and library communities could benefit from readable, user-friendly publications, online workshops and training, conference presentations, and other resources to build programs grounded in youth development, best practice, and PYD research; (2) Targeted grant programs and strategic alliances among national museum and library organizations and other efforts with expertise and commitment to youth development could further strengthen youth and their communities; and (3) Additional skills to build community support, capture media interest, involve elected and appointed decision makers, maintain institutional support, and develop new partnerships could help library and museum staff strengthen and sustain youth development programs. The following are appended: (1) Questionnaire; (2) Youth Action Committee; (3) Case Study Interview Guide; and (4) Case Studies. (Contains 9 figures and 7 tables.)