The authors examine the effects of the ACA Medicaid expansion and changes in federal grant levels on the community health center patient volume, insurance coverage, and visits from 2012 to 2015. In the period after expansion (2014–15), health centers in expansion states had a 5 percent higher patient volume, larger shares of Medicaid patients, smaller shares of uninsured patients, and increases in overall visits and mental health visits, compared to those in no-expansion states. Increases in federal grant funding levels were associated with increases in numbers of patients and of total, medical, and preventive service visits.