This is a competitive renewal of NIH T32DK-07519, requesting funding for years 26-30 for 4 pre- and 5 post- doctoral positions, and also 3 short-term summer slot positions for minority students. The aim is to continue training the next generation of scientists in the clinically-relevant medical area of the regulation of hematopoietic cell production. Pre- and post-doctoral trainees will be trained 3-4 and 2-3 years, respectively.We assembled an outstanding group of 27 productive/interactive investigators from 7 departments of the medical school (Microbiology/Immunology, Biochemistry/Molecular Biology, Pharmacology/Toxicology, Medical/ Molecular Genetics, Medicine, Pediatrics, and General Surgery) who have trained pre- and/or post- doctoral students with multidisciplinary approaches using different cell types, and who have collectively co- published over 1000 papers with their students. Training emphasis is on hematopoietic stem (HSCs) and other blood cells, but includes studies with other cell types to enhance collaboration/training experiences. The PD studies HSCs and hematopoiesis, published >650 papers, is on numerous editorial boards/NIH/other review/advisory committees, is President of ASH, and has trained 66 pre/post docs. The Co-PD is well- recognized in the hematopoiesis area, has published >140 papers, trained >20 students/fellows, and served on numerous grant review committees. Our preceptors are funded, have extensive collaborations, co-publish with each other, have our labs within 5-10 minute walking distance, and are dedicated to training students in the area of this program. Training entails one-on-one interactions, formal committee meetings, lab meetings, special seminar series and journal club, didactic courses, ethical training and scientific meeting presentations. An Internal and External Advisory Committee monitors student/mentor and PD/Co-PD progress. Many of our past students are employed in academia. This training will enhance the future of hematopoietic cell regulation for basic understanding and translation for treatment of disease.