This executive summary presents the broadest look yet at a growing trend in America's cities: the emergence of city-led efforts to build comprehensive afterschool and out-of-school time (OST) systems that meet the needs of children and youth in their communities. Mayors and other municipal officials who have demonstrated leadership in this area are increasingly linking isolated programs within more coordinated citywide networks, bringing disparate stakeholders together to create and advance common strategies, and using research-based approaches to improve program quality and access. In preparing the report, commissioned by The Wallace Foundation, the National League of Cities (NLC) identified 27 cities--from Philadelphia to Portland, Oregon, and Bridgeport, Connecticut, to Jacksonville, Florida--that have made impressive strides in the development of citywide OST systems. Staff from NLC's Institute for Youth, Education and Families surveyed and interviewed representatives from each city to understand more fully the nature and pace of change within these communities. The descriptive city profiles generated through this research provide a rich portrait of what progress looks like in these leading cities, some of which have been engaged in OST system-building initiatives for only a few years while others have labored for as long as a decade to achieve their current results. (Contains 1 footnote.) [For the main report, "Municipal Leadership for Afterschool: Citywide Approaches Spreading across the Country," see ED537016.]