Cities pursuing common enrollment systems face challenging questions about who has the responsibility for implementation, and how the system can adapt and change over time for long-term success. These questions are made all the more challenging when schools in different sectors are competing for students and when cross-sector trust is low. This brief looks at how three cities—Denver, New Orleans, and Washington D.C.—have addressed key governance issues as they designed and implemented their common enrollment systems. This is the third in a series of issue briefs on the policies surrounding design and implementation of common enrollment systems.