During summer and fall 2002, Urban Institute staff visited three communities for The Wallace Foundation to learn as much as possible about existing community-based programs for children and youth and the interconnections among them. This brief describes the goals of this work, what we did to accomplish them, and what we learned in the process. It focuses particularly on the technique of "community mapping" as we used it. We present results obtained for the three communities visited, not for their own sake but as illustrations of how other communities or funders might apply the technique to expand and improve their programming for children and youth. Because of its graphical nature, community mapping reveals otherwise hidden patterns in community programs, which can lead to more informed and effective decisions about these programs.