PROJECT SUMMARY/ABSTRACT This AHRQ Mentored Research Scientist Career Development Award (K01) will establish Dr. Alex McDowell as a national expert in sexual and gender minority (SGM) health policy, leading health services research that identifies policy approaches to address SGM health inequities. With the support of this K01, Dr. McDowell will use Medicaid claims and encounter data to evaluate the impact and implementation of gender affirming coverage policies in Medicaid, generating novel and timely evidence that stakeholders can use to inform federal and state policies. Using the staggered introduction of gender affirming coverage policies across states, 2016-2022, this study will employ difference-in-differences methods to estimate the effect of these policies on use of gender affirming health care services (e.g., hormones and surgery) among gender minority (i.e., transgender and gender diverse, GM) individuals. Given notable mental health inequities among the GM population in the U.S. and the demonstrated link between use of gender affirming services and improved mental health outcomes for GM individuals, Dr. McDowell will also study the effects of adoption of gender affirming coverage policies in Medicaid on adverse mental health outcomes, including psychiatric hospitalizations and suicidality, among GM enrollees. Lastly, Dr. McDowell will use the Consolidated Framework for Implementation Research (CFIR) and semi-structured interviews with Medicaid stakeholders to identify barriers and facilitators to implementation of gender affirming coverage policies in Medicaid, including differences across Medicaid financing models (e.g., fee-for-service vs. managed care). This project will combine rigorous quasi-experimental policy evaluation with contextual data on the barriers and facilitators to implementation to provide a comprehensive understanding of the impact of Medicaid gender affirming coverage policies on GM health and health care. The proposed research builds upon and extends Dr. McDowell’s training in health services research methods and prior research in GM health policy among commercially insured individuals. Her training plan will support her goals of developing expertise in Medicaid financing and managed care, acquiring skills in the measurement of gender affirming care, and gaining proficiency in implementation science research. Through the research and training in this K01, Dr. McDowell will be prepared to lead studies that systematically evaluate the effects and implementation of ongoing policy changes affecting GM individuals at the state and federal levels and to be a leading expert in sexual and gender minority health policy.