In the 1990s, NewYork-Presbyterian Hospital began developing a comprehensive, standards-based immunization information system. The system, known as EzVac, has been operational since 1998 and now includes information on 2 million immunizations administered to more than 260,000 individuals. The system exchanges data with multiple electronic health records, a public health immunization registry, and a standalone personal health record. EzVac modules have recently been incorporated into the OpenMRS application and are being used to enhance immunization efforts in developing nations. We report on our experience with developing and using the EzVac system for 1) clinical care, both in local and global settings, 2) public health reporting, 3) consumer engagement, and 4) clinical and informatics research. We emphasize the advantages of using health IT standards to facilitate immunization information exchange in each of these domains.