Early-life exposure to environmental pollutants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or diets high in fat has been associated with an increased risk of cancer. La Merrill et al. (p. 596) investigated how developmental exposure to TCDD and a high-fat diet (HFD) might interact to alter breast cancer susceptibility in a laboratory animal model.