This analysis of Denver, Houston, and Los Angeles finds that the degree to which financial and organizational flexibility and managerial agility can be combined with a mission of public service under the constraints of public financing appears to be key to a successful ambulatory care safety net. An ability to strictly define the eligible population and to enforce eligibility standards also strongly influences success. The assets of the Denver system include strong leadership, the integration of ambulatory care with inpatient and specialty care, strong local financial and political support, and a geographically limited service area. Los Angeles has some of the assets of the Denver system, but is currently in a state of transition. Houston has fewer assets but has an opportunity for change under its new system leadership.