Since the first charter school law was passed in 1991, the relationship between charter schools and districts has been rife with conflict. To no one's surprise, districts have fiercely resisted competition from public schools of choice, especially when that competition grows beyond just a small number of schools and poses a real threat to the district's financial stability. For their part, charter schools have fought just as fiercely against any attempt to impose on their autonomy. As the charter school movement has matured and expanded over time, a growing number of district and charter leaders have slowly and quietly been forging agreements to work together. In many cases, mayors, superintendents, civic leaders, and others reach out to charter leaders to work across traditional charter-district divides. Collaboration touches one or more of these common themes: shared resources, shared responsibility, shared effort to build trust and collegiality, and shared work to ensure equal access to high-quality schools for all students in the city. More than 23 cities have signed District-Charter Collaboration Compacts--formal agreements between school districts and charter schools that aim to share resources and responsibility and build trust and collegiality to ensure equal access to high-quality schools for all students. Within the charter sector itself however, there are highly varied perspectives on and motivations for collaboration. Based on dozens of interviews and observations over four years, the authors look at why many cities have missed opportunities to create more lasting relationships between their district and charter sectors, and offer suggestions for fostering stronger partnerships that could help improve outcomes for all of the students in their cities. Key findings include the following: (1) Many well-intentioned partnership efforts fall short of their full potential because districts see and treat the charter sector as a monolith, rather than a group of distinct, independent actors with diverse motivations, interests, and perspectives; (2) Creating a unified coalition of charter schools led by independent-minded individuals is difficult but not impossible; and (3) Moving forward requires more nuanced strategies tailored to the needs of the players on the ground. For that reason, collaboration agreements and approaches will necessarily vary from city to city. Suggestions for mayors, district leaders, and charter association heads to create more sophisticated collaboration strategies include: (1) Looking for unifying citywide "bread and butter" issues such as funding or enrollment caps that can involve all charter schools; (2) Creating school or network collaborations when a citywide approach is not possible; (3) Creating opt-in opportunities for highly contentious issues; and (4) Cultivating effective leadership to build coalitions.