The National Bioethics Advisory Commission (NBAC) was established by executive order in 1995 to advise the National Science and Technology Council and other government entities on bioethical issues arising from research on human biology and human behavior. During the commission's five-year tenure, it submitted six major reports to the White House that contained 120 recommendations on several complex bioethical issues, including the cloning of human beings, research involving persons with mental disorders that may affect decisionmaking capacity, research with human biological materials, embryonic stem cell research, U.S.-sponsored clinical trials in developing countries, and protection of human research participants. This RAND study was conducted to assess NBAC's contribution to the policymaking process as it relates to these issues. The author provides a detailed account of the responses to each of NBAC's six reports from the president, Congress, government, societies and foundations, other countries, and international organizations. Although no legislation has been passed based on NBAC's recommendations, agencies responsible for a major portion of federally funded research involving human participants-particularly the National Institutes of Health-have adopted several of NBAC's recommendations and issued research guidelines based on those recommendations.