Under the auspices of the Society for Women's Health Research, a thought leaders' roundtable was convened at the National Institute of Environmental Health Sciences in October 2002 to discuss recent advances in environmental health research, particularly those findings that explain sex differences in response to environmental exposures. Researchers discussed the latest findings on the interaction between sex and environmental exposures on health. Participants concluded that a greater focus on interdisciplinary, hypothesis-driven research is essential to advancing the field. To understand fully the potential effect of chronic exposures, researchers need to develop models to explore not only physiologic sex differences but also behavioral responses to low-dose and multiple chemical exposures. Future research should examine sex differences from the cell line to behaviors and should track these differences across multiple generations. Federal agencies should support such research in their awards of investigator-initiated grants.