New molecular approaches and clinical considerations have re-invigorated research into hematopoietic cell development and activity, opening up to rational investigation areas that previously seemed opaque. To capitalize on these new opportunities it is necessary to train a new generation of scientists, imparting to them an appreciation for the beauty of the hematopoietic system, an understanding of key unresolved issues in blood formation and component cell function, and an awareness of how to utilize cutting edge scientific techniques in the service of hematological research. This program is designed to do just that, by building on a highly successful training program in existence here since 1980. Trainees will be pre-doctoral (4) and post-doctoral (4) fellows, the latter with either M.D. (2) or Ph.D. (2) degrees. Candidates will be screened by appropriately constituted committees of the training faculty, with substantial effort directed toward recruiting members of underrepresented minorities. Trainers represent a select group of 18 scientist/mentors who use multidisciplinary approaches in their own research in the areas of Myeloid Development and Function, Hematological Malignancies, Coagulation and Platelets, and Apoptosis. Pre-doctoral students will be admitted to the program and simultaneously to either of two collaborating departments--Medicine and Microbiology. Pre-doctoral students will take courses and then carry out mentored research culminating in a thesis dissertation. Post-doctoral fellows will carry out research supervised by one of the training faculty for a minimum of two years. Both pre- and post-doctoral students will attend the new Molecules to Molecular Therapeutics course which is an in depth study of hemoglobinopathies. Didactic coursework and mentored research experiences will be supplemented by a network of Hematology research roundtables, seminars, and journal clubs, lectures on preparing manuscript and grant submissions, departmental and other seminars, plus training in the responsible conduct of science. Trainees will work in modern, spacious laboratories accompanied by luncheon and other areas conducive to informal interaction. By fostering Hematology as an investigational science, long term progress is expected in understanding the normal development and function of blood cells, and abnormalities associated with disease.