High-quality out-of-school-time (OST) programs have a positive effect on youth development, but many cities have found it difficult to address the challenges of expanding and improving the quality of programs offered to underserved and high-need students. In response, The Wallace Foundation sponsored an initiative to help five cities increase collaboration, access, quality, information sharing, and sustainability in their OST systems. The third in this three-volume series presents in-depth case studies of the five Wallace Foundation grant cities: Providence, Boston, New York City, Chicago, and Washington, D.C. A review of the history of the grant in each city, the role played by the local context in which it was implemented, the initiative's progress toward a range of goals, and enablers and challenges to implementation reveals both lessons learned and best practices for the OST field. For example, strong interagency coordination and mayoral involvement, gaining stakeholder buy-in, a comprehensive approach to training and professional development, and shared goals were all associated with the more successful OST improvement efforts. However, all the cities faced challenges in implementing their respective initiatives, including staff turnover at the agency and program levels, funding constraints, obstacles to coordination, and issues related to data entry and tracking student outcomes. Individual chapters contain footnotes. (Contains 10 figures and 5 tables.) [For the related reports, see Volume 1 (ED514586) and Volume 2 (ED514587).]