Women's health and men's health differ in a variety of ways--women live longer on average, for example, but tend to be sicker as well. Whereas some of these distinctions are based solely on gender, there is growing awareness that the environment and related factors may play a role in creating health status differences between men and women. Various factors, such as genetics and hormones, may account for gender differences in susceptibility to environmental factors. In 1996 the Office for Research on Women's Health at the National Institutes of Health asked the Institute of Medicine to conduct a workshop study to review some of the current federal research programs devoted to women's health and to clarify the state of knowledge regarding gender-related differences in susceptibility. This book contains a general outline of research needs, a summary of the workshop proceedings (as well as summaries of the speakers' presentations), and an analysis of the participating federal agencies' research portfolios.