Abstract Introduction We sought to identify the share of National Institute of Mental Health (NIMH) funding allocated to U.S. policy research over the past three decades (1993-2024).Methods We systematically searched the National Institutes of Health Research Portfolio Online Reporting Tools Expenditures and Results database using keywords. Manually reviewing the titles, abstracts, and publications of all projects identified through this search, we categorized a project as U.S. policy research if it studied the outcome(s) and/or implementation of a policy and if it had a mental health focus. We measured the share of NIMH projects and funding allocated to policy research as a percentage of all NIMH projects and funding between 1993 and 2024. We also examined whether NIMH projects and funding for policy research changed between 1993 and 2024.Results Aggregating all NIMH funding between 1993 and 2024, NIMH funded 107,284 projects and allocated $39.87 billion to research, of which 1,510 projects (1.36%) and $800.59 million (2.04%) were policy research. NIMH funded 29 policy projects ($16.27 million) in 1993 and 62 policy projects ($33.69 million) in 2024, a 113.79% increase in policy projects.Conclusion NIMH allocates a small share of research dollars and projects to U.S. policy research despite policies’ importance to population mental health.