Disease rates, including rates of such common cancers as breast and colon cancer, vary widely across ethnic populations in the US. While genetic factors may play a role, the tendency for cancer rates in migrant populations to converge with those of the host population suggests that different disease rates may also arise from differences in behaviors and lifestyles. Dietary differences are especially interesting for their potential to explain the distribution of disease both across ethnic groups and within ethnic groups undergoing cultural transitions. The objectives of this research, broadly, are to investigate the role of diet in the distribution of cancer in ethnic populations, and to explore the use of dietary patterns as an alternative method for characterizing dietary intake in nutritional epidemiologic studies. The influence of the larger social and economic environment on health-related behaviors is also relevant for understanding transitions in health-related behaviors and disease rates in ethnic groups and is, therefore, an additional subject of investigation in this research.