With 20 million more people insured today under the Affordable Care Act, health care providers have had to adapt to the increased demand for health care services. Based on provider interviews in five communities that saw some of the largest percent increases in the number of insured people since 2013, we found that providers expanded their staff, hired more advanced practice clinicians, opened new and expanded existing clinics, extended office hours, and achieved efficiencies through health care payment and delivery reforms. The number of urgent care and retails clinics grew, but telemedicine did not expand substantially. Behavioral health services remained the most significant unmet need. Respondents identified persistent health care professional workforce shortages and possible cutbacks to Medicaid as major challenges going forward.