Elderly persons of African American and Latino descent have lower rates of immunizations after adjustment for insurance and education. Interventions that use faith-based organizations (FBOs) are promising but have not been well evaluated. We examined the effectiveness of an FBO adult vaccination program in minority communities. From December 2003 through January 2004 and November 2005 through February 2006, 15 churches were randomized to intervention with onsite adult vaccinations or to comparison with no vaccinations. Participants were eligible if they had not been previously vaccinated with pneumococcal vaccine, did not regularly receive influenza vaccine, were aged > or =65 years, and had a clinical indication for vaccination. Baseline and follow-up surveys were conducted. Primary outcome was rates of influenza and pneumococcal vaccinations. The study sample (N=186) was 44% African American, 43% Latino, 8% White, and 3% Asian. Of those eligible, 90 of 112 (80%) in the intervention group used the influenza vaccine compared to 32 of 70 (46%) in the comparison group (P < .001). Of those eligible, 58 of 88 (66%) in the experimental group used the pneumococcal vaccine compared to 20 of 57 (35%) in the comparison group (P < .001). Participants in the intervention group were significantly more likely to receive influenza vaccinations (odds ratio [OR] 4.8, 95% confidence interval [CI] 2.5-9.4) and pneumococcal vaccination (OR 3.6, 95% CI 1.8-7.2). More than ninety percent of all participants reported willingness to participate in FBO education and promotion programs. This onsite, FBO adult vaccination program was effective in increasing vaccination rates and may be promising for decreasing raciallethnic disparities in vaccination rates.