Since the U.S. Congress first requested an assessment of women's health content in medical school curricula ten years ago, surveys indicate at least a two-fold increase in the number of schools with a women's health curriculum and no change in the number that offer a women's health clinical elective or rotation. Despite a marked increase in the number of schools with an office or program responsible for integration of women's health and gender-specific content into curricula, change has been modest. Reasons for this slow progress include uncertainty about the domain of women's health and what should be included in a curriculum, a lack of practical guidelines for implementation, and institutional resistance to change. The dominant factors that will influence future curriculum development are the increasing scientific knowledge base on sex and gender differences and the emerging scientific field of sex-based biology, both of which have potential to benefit the health of women. Evidence-based data on significant sex and gender differences will provide compelling reasons for schools to integrate this information into curricula, and new educational initiatives must further develop educational models to help implement change. As women's health becomes synonymous with the term "sex and gender differences," the challenge to schools is to address equally in their curricula those unique aspects of women's health that were part of the original intent of the congressional mandate.