Building capacity in immunization and IIS programs housed in state, tribal, local and territorial (STLT) public health agencies - Immunization information systems (IIS) are a crucial component of public health infrastructure in the U.S., enabling national progress on childhood immunization rates. During the COVID-19 pandemic, the essential nature of IIS became even more evident, as these systems served as a core component of the emergency public health response. CDC has long prioritized advancing the capabilities of IIS and improving the quality of the data they contain. CDC’s long-term vision includes standardized, interoperable systems that capture, use and exchange immunization data across the country. The Public Health Informatics Institute (PHII) proposes to draw upon its 32 years of IIS and public health informatics expertise and experience to join CDC in this goal of advancing IIS. Since PHII first launched in 1992 as the Robert Wood Johnson Foundation-funded program All Kids Count, it has been PHII’s primary mission to provide direct technical assistance and training for practitioners building and maintaining IIS. Three decades ago, PHII played a critical role in fostering the first IIS programs around the country, and today, we continue to support the vital role of IIS in the public health landscape through guidance, toolkits, direct support and workforce development. In 20 years of partnering with CDC on this work–including 16 years under a CDC cooperative agreement–we have seen immense success on this front, and we have established ourselves as a trusted partner of the IIS community. The purpose of this proposal is to describe a strategic and coordinated set of planned activities to further build capacity in immunization and IIS programs housed in state, tribal, local and territorial (STLT) public health agencies, and to modernize and improve the data quality and interoperability of IIS, by addressing three components of CDC’s vision for IIS: 1) community engagement and support; 2) workforce development; and 3) education. The proposed strategies and activities respond to the priority needs of immunization and IIS programs in public health jurisdictions, as they have been identified through PHII’s prior work with these populations. Consistent with the CDC’s Public Health 3.0: A Call to Action to Create a 21st Century Public Health Infrastructure, PHII proposes to: a) improve IIS workforce capacity to address expected and emerging standards of IIS programs; b) increase use of IIS standards, resources and technical assistance (TA) available to jurisdictions; c) enhance workforce resources to meet recruitment and retention needs; d) develop workforce staffing resources to support all IIS functional roles and responsibilities; e) increase use of toolkits by immunization jurisdictions to support best practices in IIS workforce development; f) increase jurisdictions’ IIS staff use of educational materials and training offerings; and g) increase engagement at CDC meetings with jurisdictions to provide guidance on national standards and the Federal Section 317 Immunization Grant. Long term outcomes are to increase IIS community engagement, build workforce capacity, increase IIS staff knowledge, and ultimately promote a strong and effective IIS network across the nation.