Increasing the representation of women and racial and ethnic minorities in human research has become a national priority. Federal agencies have made inclusion of women and minorities an explicit criterion on which applications for clinical research funding are judged.1 The need for this affirmative action stems from a historical bias favoring white men. As with most other institutions in the United States, medical research no longer actively excludes women and minorities. But the history of these institutions, the way they were designed and built—predominantly by and for white men—slants them in a way that continues to limit access for other groups. Federal efforts to remedy this institutional bias have not been very successful. Data from cancer clinical trials suggest that minority representation in research has not only failed to increase but has actually declined over time.