Small businesses play a critical role in developing innovative technologies that support national defense and strengthen the U.S. industrial base. For more than four decades, the Department of Defense Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) programs have helped connect entrepreneurial firms with defense needs, advancing new capabilities while expanding opportunities for participation in the defense innovation ecosystem.Review of the SBBR and STTR Programs at the Department of Defense presents a comprehensive, congressionally mandated assessment of how these programs operate and the impacts they deliver. The report finds that the Department of Defense's SBIR and STTR programs are effective tools for stimulating technological innovation, engaging small businesses, and broadening the defense industrial base, while identifying opportunities to improve data systems, technology transition, program visibility, and administrative efficiency. Drawing on extensive quantitative and qualitative evidence, the report offers targeted recommendations to strengthen program management, enhance flexibility, and ensure that promising innovations can move more effectively from research to operational and acquisition use.