In thousands of medically underserved communities across the U.S., community health centers enroll low-income people in health coverage and provide care to millions of patients. Against the backdrop of significant health center expansion over several years and a full year of expanded health coverage under the Affordable Care Act (ACA), this brief examines change between 2013 and 2014 in the volume and health coverage profile of health center patients, and health center enrollment activities and service capacity, comparing states that implemented the ACA Medicaid expansion in 2014 and states that did not expand Medicaid in 2014. The study is based on data from the federal Uniform Data System and a 2014 national survey of health centers.