From 1997 to 2001, the National Association of County and City Health Officials, in collaboration with the Centers for Disease Control and Prevention's Public Health Practice Program Office, developed a new community strategic planning tool, titled Mobilizing for Action through Planning and Partnerships (MAPP). This article provides a chronological description of the development of MAPP, devoting significant attention to pivotal decisions, development milestones, and distinguishing features of this new public health planning tool. All phases of the development ensured a practice-driven process, ongoing substantive input from the field, careful attention to research and literature, and intentional linkage with related efforts. This deliberate process laid the foundation for a tool that is not only well grounded in research and concepts but also relevant for practical use in communities. The process also demonstrates how practice-based research can be conducted in a way that effectively balances the need for applied relevance with intellectual integrity.