The program began in 1995. We now seek funding for a third, five-year period. The program provides interdisciplinary training in behavioral, biobehavioral, and social science research on MRDD, with an emphasis on social-affective, communication, and family processes. Post-doctoral trainees enter the two year program with a Ph.D. in a discipline related to human behavior and child development. The training program is housed and fully integrated into the Waisman Center at the University of Wisconsin-Madison, which is supported by an NICHD-funded P30 Core Grant. All 21 members of the program faculty are Waisman Center investigators and conduct externally funded programs of research. The goal is to develop the skills and enduring commitment needed to conduct high quality, programmatic, and fundable research on MRDD. The program has four key elements: (1) mechanisms for coordinating and monitoring individualized training experiences for each trainee; (2) intensive research training experiences; (3) participation in a core curriculum of seminars; and (4) completion of tangible "products." All 14 trainees who have completed the program have gone on to faculty or research scientist positions at first-rate universities, including Boston University, Pennsylvania State University, University of North Carolina at Chapel Hill, and University of Wisconsin-Madison. Trainees have published relevant research in prestigious periodicals both during and after their traineeships. Five have already secured NIH funding for their research. Three trainees are members of underrepresented groups. Faculty collaboration with trainees has been extensive. Two former trainees are now members of the training program faculty, and a third is a member of our National Advisory Committee and will assist with recruitment of post-doctoral candidates of color. The program, like the science it supports, is dynamic. Thus, we have added a biobehavioral dimension to the program, with this dimension supported by additions to the program faculty, changes to the curriculum, and recruitment of relevant trainees. We also have greatly expanded the focus on responsible conduct of science.