Throughout her career, Dr. Ziegler’s research has focused broadly on dietary, nutritional, anthropometric, and hormonal determinants of cancer risk. Her early work helped characterize the role of vegetables and fruits, individual carotenoids, folate, and one-carbon metabolism in cancer etiology. In addition, she has conducted a number of breast cancer studies with emphasis on anthropometry, diet, and endogenous hormones and growth factors. For example, Dr. Ziegler helped design and direct a large, population-based case-control study of breast cancer in Asian-American women to elucidate the modifiable exposures, related to lifestyle and/or environment, that explained the six-fold difference in breast cancer incidence between Asia and the West. More recently, she collaboratively developed an international pooled analysis of circulating vitamin D concentrations in relation to risk of colorectal and breast cancer. Dr. Ziegler has applied her training in chemistry and biochemistry to the development of new and improved methods for measuring various hormones and nutrients in epidemiologic studies. Recently, she played a critical role in the successful development of a sensitive assay for assessment of estrogen metabolites and a validated assay for concurrent measurement of the major steroid hormones. Dr. Ziegler is a fellow of the American Society for Nutrition and helped establish its Nutritional Epidemiology Research Interest Section. She currently serves on the editorial boards of the Journal of the National Cancer Institute and the Nutrition Action Healthletter, and previously served on the editorial boards of the American Journal of Clinical Nutrition, the Journal of Nutrition, and Cancer Epidemiology, Biomarkers, and Prevention. She received a NIH Merit Award for her research on the role of vegetables, fruits, and micronutrients in the etiology of a variety of cancers.