Project Summary/Abstract The long standing goals of this training grant are to provide support and training to academically strong and highly motivated predoctoral and postdoctoral researchers in the field of endocrinology and related subjects dealing with all aspects of hormone biology at the organ, cellular, molecular levels through modern genetic tools in various model organisms. We aim to provide our trainees with a broad intellectual background that includes coursework, experimental expertise, seminars, grant craftsmanship and career advice. The program is implemented by our outstanding training faculty and the rich research infrastructure at Columbia University. The training faculty are highly collaborative and national and international leaders in research exploring the mechanisms of steroid, retinoid, thyroid and polypeptide hormones as well as the paracrine interactions associated with growth factors, cytokines and important signaling transduction pathways and inter-organ communications. The trainees can work in diverse experimental systems across model organisms and human subjects. We continually update our training faculty to reflect the evolving trends in research in endocrinology and the changing Columbia faculty base. This training program has been in effect for 42 years and the accomplishments of our trainees during this time have been outstanding, with many of them currently holding NIH funded tenure track faculty positions in premier academic institutions. During the past cycle (2015-2019), A total of 19 unique trainees have been supported or are currently being supported by the training grant. The recently funded trainees have all been extremely productive in their research programs. All previous trainees continue to pursue science related careers. Most of our postdoctoral fellows have attained individual research grants. We continue to work with our fellows to help them achieve success in their current and future research careers. Overall, the training program emphasizes excellence in scholarship and research and career advising. In addition, participation in the program exposes trainees from diverse disciplines to practical applications in endocrinology and highlights translational aspects of their research. Due to the steadily increasing demand for training grant slots, we are requesting additional positions to accommodate our highly qualified pool of applicants.