Panelists explored the complex interaction among the potential contributors to breast cancer risk. Robert Hiatt of the University of California at San Francisco talked about the complex etiology of breast cancer and Linda Birnbaum, Director of the National Institute of Environmental Health Sciences, gave a presentation on early-life exposures to endocrine-active chemicals and how they promote breast cancer risk later in life. Mary-Claire King of the University of Washington talked about gene-environment interactions in breast cancer risk and Joyce Tsuoyi of Exponent talked about new directions for future research on environmental influences on breast cancer.