This report, funded by the Annie E. Casey Foundation, outlines the benefits of using a coalition building approach to foster long-term, cross-sector engagement in communities. It highlights data and experiences from six communities who used a coalition building approach to improve youth well-being, inclusivity, and participation, particularly among racially and ethnically diverse groups. The guide emphasizes the importance of quality operations, early engagement, and data-driven decisions, drawing on real-life examples and provides guidance for other communities to consider context, history, and power dynamics while providing strategies for sustainable, positive change.