The Belmont Report, produced in 1979 by a United States government commission, includes minority populations among its list of vulnerable research participants. In this article, we consider some previous attempts to understand the vulnerability of minorities in research, and then provide our own account. First we examine the question of the representation of minorities in research. Then we argue that the best understanding of minorities, vulnerability, and research will begin with a broad understanding of the risk of individual members of minority groups to poor health outcomes. We offer a typology of vulnerability to help with this task. Finally, we show how researchers should be guided by this broad analysis in the design and execution of their research.