The objective of this program is to prepare post-doctoral trainees to establish independent research careers in the areas of gonadal function, early pregnancy and embryonic development through implantation. The training program will consist of three elements;independent laboratory research, group seminars and other functions held jointly with the Center for Reproductive Sciences, and formal course work in research ethics and animal welfare, as well as subjects that will enhance the trainee's research expertise. The independent research will occur in a laboratory selected by the trainee from a group of 12 scientists who are leaders in various aspects of reproductive and developmental biology. The members of this training group have well established NIH-funded programs and have trained more than 86 postdoctoral fellows. Areas of study include fertilization, pre-implantation development, trophoblast-uterine interactions, the immunobiology of implantation and early pregnancy, as well as regulation of gonadal function, gene expression during testis and embryonic development. The strength of this group is enhanced by collaboration among the members as evidenced by the record of joint publications, grants, and students. This program will take advantage of an existing Center for Reproductive Sciences comprising 21 principal investigators and 78 additional staff and trainees to provide an enhanced training environment. The Center for Reproductive Sciences sponsors an active seminar program and hosts a regional conference in reproductive biology, which provides additional opportunities for trainees to present their work. The recruitment, selection and guidance of trainees will be coordinated through an Internal Advisory Committee, with input from all participating faculty and in consultation with an External Advisor, who will meet with the group once each year. Applicants who have been awarded a Ph.D. degree in one of the biological sciences, or a D.V.M. or M.D. degree and who demonstrate a commitment to research in reproductive biology will be considered for entry into the program. An emphasis will be placed on recruiting under represented minorities into the program. The records of the six trainees selected during the first funding period are impressive, with two of the four trainees who have completed their training having assumed faculty positions, one tenure track and one research track. The overall success of the program will ultimately be measured by the contributions of these trainees after they have established independent research programs.