Amidst recent policy discussions about the health care safety net there has been relatively little information about whether the actual site of care affects care quality. We therefore used National Health Interview Survey data to describe low-income adults seeking primary care at different types of sites and the quality of access and preventive care at these sites. After adjusting for sociodemographic characteristics and illness burden, hospital-outpatient- department patients were more likely to receive vaccinations for influenza (adjusted odds ratio [AOR] 1.3, 95% confidence interval [CI] 1.0–1.6) and pneumococcus (AOR 1.4, 95% CI 1.1–1.8) than were those at clinics or health centers. Hospital-clinic patients were more likely to report delays in care due to office administrative difficulties (AOR 1.3, 95% CI 1.1–1.7) and more likely to have more than one emergency room visit (AOR 1.9, 95% CI 1.5–2.3). Physicians’ office or HMO patients were less likely to report administrative delays in care than those at clinics or health centers, but there were no other differences in quality between these two site types. Policymakers and health care services analysts and providers must monitor quality as they decide how best to deliver care to vulnerable populations.