The overall aim was to determine whether health care delivery for vulnerable populations served by community health centers (CHCs) was comparable to care for mainstream Americans primarily seen in physicians' offices (POs). Data came from the 2006 National Ambulatory Medical Care Survey. Patient visits occurring in CHCs were largely from younger, uninsured or Medicaid-insured, minority populations, while POs catered mainly to older, Medicare- or privately-insured, White patients. Communities served by CHCs were more often in low-income, low-education, urban regions. A greater proportion of visits to CHCs were from diabetic, obese, and depressed patients; CHCs also offered more evening/weekend visits and provided more health education during visits, but spent less time per visit than POs and had more difficulty referring patients to specialists. Results affirmed the significant role of CHCs as safety-net providers for vulnerable populations, and indicated that CHCs provide adequate care compared with POs although there remains room for improvement.