In 2008 San Mateo County, California launched its Adult Coverage Expansion and Systems Redesign Initiative. The initiative expanded coverage for all uninsured adults below 200 percent of the poverty level and redesigned care in county safety net clinics. The program substantially improved access to care for uninsured adults, as well as improved continuity and quality of care for those served by county safety net clinics. However, access remains a problem for new enrollees, due to restrained provider supply and the economic recession. The report provides lessons for other counties as they expand coverage under national health reform.