This training grant in developmental endocrinology and metabolism at Boston Children's Hospital (BCH) intends to provide funding for 4 postdoctoral fellows per year to engage in research training leading to independent careers in academic pediatric endocrinology. The program is designed to address the shortage in academic pediatric subspecialists, including pediatric endocrinologists, and train future physician-sicentist leaders who will use research to address pressing problems such as obesity and diabetes. The trainees (4 slots per year) are largely selected from a pool of 6 to 9 highly qualified pediatric endocrinology postdoctoral fellows who are in the BCH Division of Endocrinology Fellowship Program or less than one year after completion of the program. The intended average duration of training is two years. Trainees enter the program with either the MD (or equivalent), MD/PhD or occasionally the PhD degree. The 32 trainers include 13 clinically active pediatric endocrine physician-scientists, 10 physician-scientists of other disciplines, 11 MD/PhDs, and 6 PhD scientists. BCH is the major training site, but fellows also train at Massachusetts General Hospital, Beth Israel Deaconess Medical Center, Brigham and Women’s Hospital, Joslin Diabetes Center, and the Whitehead Institute. The major areas of research emphasis in this training grant include clinical, translational and basic laboratory research in diabetes mellitus and its complications, obesity and its complications, diet/metabolism and health, neuroendocrinology, skeletal health and biology, intestinal biology and developmental endocrinology, sex differences and endocrine disease, and endocrine cancers. Training consists of didactic courses, including in quantitative methods, ethical conduct of research, and reproducibility/rigor, and an intensive period of individually mentored research. Of the 34 trainees during the past 15 years who have completed training on this T32 grant, 30 are faculty in academic pediatric or research institutions, two are in industry, and one is at the FDA. Of these 30, there are 13 Assistant Professors, 5 Associate Professors, 1 Professor, 2 Division Chiefs, and 10 Program Directors. Their record of publication is strong, as is their record of grant funding: 12 have had independent NIH K awards, 4 have had R03 or R21 awards, and 5 have one or more R01s. This program takes advantage of the breadth of scientific expertise of the training faculty within the Division of Endocrinology, as well as in the larger BCH community and surrounding Harvard environment. We provide trainees with a rigorous and stimulating training environment, with many excellent courses, cutting-edge seminars, and outstanding mentors who deploy the latest research methods. With highly qualified trainees and a track record of past success, we hope to continue to train a next generation of diverse academic pediatric endocrinologists and physician-scientist leaders.