PROJECT SUMMARY The substantial time and effort required to harmonize data for global multi-cohort collaborations can lead to research delays, particularly given heterogeneity in data, data management capacity, and data sharing regulations. The goal of the Harmonist project is to develop data standards, software, and methods that help HIV observational research consortia to coordinate multiregional research projects and apply data management best practices more effectively and efficiently. To promote reusability, Harmonist tools are built (when feasible) as shareable External Modules for the widely used Research Electronic Data Capture (REDCap) software, which is in use at over 4,450 institutions in 138 countries as of mid-2020. The initial Harmonist suite of tools includes the Harmonist Hub, a platform for scientific project and portfolio management, and the Data Toolkit, a web-based system for data quality checking and secure data exchange. The Harmonist project aims to (1) strengthen data harmonization and consortium support for the International epidemiologic Databases to Evaluate AIDS (IeDEA) consortium, including providing a new data framework for IeDEA prospective studies, (2) expand support to the Regional Prospective Observational Research for Tuberculosis (RePORT) International consortium, which studies TB in the context of HIV, and (3) support bi- directional mentorship and sharing around Harmonist tools, data management best practices, and data standards. This proposal is a collaboration among research informatics experts at Vanderbilt University Medical Center, all seven regional networks of IeDEA, and RePORT International. These partnerships ensure that all components of Harmonist address real-world user needs in a practical manner and provide the tools with a dedicated user base. We believe that these research tools can reduce the time and effort needed for critical data management and administrative tasks that underlie the role of observational HIV cohorts studying the global epidemic. The modular infrastructure we have designed can adapt to diverse research settings and expand to include new data types and sources as the understanding of HIV evolves. The resulting shareable software and mentoring resources will provide tangible immediate and long-term benefits to IeDEA, RePORT, and the broader HIV research community.