Recognition of the range of potential benefits linked to out-of-school experiences has led to a rapid expansion of out-of-school time opportunities across the United States. This guide outlines an approach for bringing the community together to meet out-of-school time needs of children, youth, and families. Launched in 1994, the MOST (Making the MOST of Out-of-School Time) Initiative created a model for improving and broadening out-of-school time opportunities. The guide begins with a description of the origin of the MOST Initiative and important elements of the system: (1) linkages of working groups for joint planning, priority setting, and information sharing; (2) regular creation of new working relationships, collaborations, and networks to broaden the system; (3) nurturance of leadership within the out-of-school time community; (4) a variety of programs, experiences, and opportunities; (5) high quality programming; (6) training and professional opportunities for staff; and (7) a community infrastructure including funding strategies, coordination of training, long-term planning, advocacy, and outreach, and accountability. The guide uses three methods to explain how to build an out-of-school time system. First, an outline presents a step-by-step process in three stages: (1) planning (establishing leadership, engaging community, and developing principles); (2) taking stock (community needs assessment); and (3) making it happen (setting the agenda, planning for sustainability, visibility, and sustaining change). Second, action tips are offered through recommendations based on the successes gained and challenges encountered during the seven years of the MOST Initiative. Third, MOST city models are used to illustrate how Boston, Chicago, and Seattle interpreted the process. The guide concludes with a list of print and organizational resources and information on the National Institute on Out-of-School Time. (KB)