Prior to the Affordable Care Act (ACA), health care safety-net programs were the primary source of care for over 44 million uninsured people. While the ACA cut the number of uninsured substantially, about 30 million people remain uninsured, and many millions more are vulnerable to out-of-pocket costs beyond their resources. The need for the safety net remains, even as the distribution and types of need have shifted. This brief reviews the effects of the ACA on the funding and operation of safety-net institutions. It highlights the challenges and opportunities that health care reform presents to safety-net programs, and how they have adapted and evolved to continue to serve our most vulnerable residents.