immun.com is an Internet-based immunization registry and Website that offers both patient and provider portals, reinforcing a continuum of care and enhancing compliance initiatives. The registry is HIPAA compliant, and has HL-7 and XML import and export capability. The Website is bilingual, offering educational content in English and Spanish. Efficacy was validated in a randomized trial among patients, and functionality was validated by the Illinois Department of Public Health. The registry was found to meet or exceed 100% of U.S. Centers for Disease Control (CDC) requirements. The patient education Website had a long-term positive effect on parents’ attitudes about immunizations in a two-year study involving over 500 parents. Funding for development was provided by the National Institutes of Health, National Institute of Child Health and Human Development.