Community health centers are a key source of comprehensive primary care in medically underserved communities across the country, and their role is expected to grow as health coverage expands under the Affordable Care Act (ACA). To sharpen understanding of the health center patient population, this brief compares it to the overall low-income population, using data from the Health Center Patient Survey and the National Health Interview Survey,respectively. The pre-ACA profile of health center patients that emerges sets the stage for measuring change following implementation of the reform law and can inform health center policy, planning, and assessment moving forward