Medicaid pays for nearly half of all births in the United States, including most births by Black and Hispanic pregnant population. Maternal and infant claims data contain information on diagnoses and health care utilization; however, these data alone sometimes do not provide enough information and must be linked with other data to conduct complex longitudinal patient centered outcomes research on maternal and infant health that can inform policies and programs. Linkages of Medicaid claims with other data sources have been performed at the state level using methods that vary in complexity and match rate, which makes it difficult to create a national data source for PCOR on maternal health. To better understand the current status and identify potential next steps for a consolidated approach to performing these data linkages, while leveraging long standing state efforts, ASPE contracted with RAND Health Care to: a/conduct a structured literature review of peer-reviewed and gray literature; b/ develop an inventory of data linkage efforts for all U.S. jurisdictions (defined as including all states, territories, and the District of Columbia) and detail characteristics of the data used, linkage processes, and applications; and c/ facilitate semi structured group discussions with representatives involved in these data linkage efforts from nine states to learn more details of the technical aspects of the data linkages, cross-agency processes and communications, and barriers and facilitators. The project findings are presented in this report.