Most human diseases, production traits of agriculturally important species, and fitness-related characters in natural populations, are controlled by multiple interacting genes with small, and environmentally sensitive effects. Determining what loci contribute to variation in complex traits, how they interact with each other and the environment, and what molecular polymorphisms cause the variation in phenotypes, are of fundamental importance for quantitative traits requires expertise with concepts and methodology in the traditionally separate disciplines of molecular, developmental, quantitative and population genetics, statistics and molecular evolutionary theory. The goal of this program is to provide this interdisciplinary training. The 12 training faculty have combined expertise in all of these disciplines, have active research programs focusing on experimental and statistical genetics, and interact extensively. Support is requested for seven predoctoral trainees for five years. The training program will follow the Ph.D. program in the Department of Genetics. Trainees will be selected and their progress monitored annually by the Executive Committee. Interdisciplinary training will be stressed, with advanced courses in at least three of the major disciplines required. Trainees will select their major advisor(s) and advisory committee after three laboratory rotations among the training faculty in their first semester. Collaborative research projects will be encouraged. Trainees will receive formal training in oral scientific presentation, and will participate in an annual mini-symposium on a topic related to the training program.