DESCRIPTION (Applicant's Description): The applicants are requesting continuation funds for a research training program in the Pediatric Oncology Program at the Fred Hutchinson Cancer Research Center and the Department of Pediatrics, University of Washington. The purpose of the proposed program is to train promising physicians to become independent investigative pediatric oncologists. In the first year of the program, which is funded by sources other than this grant, trainees receive intensive exposure to clinical care and clinical research. In the second and third years, they commit themselves to a major research effort. Research projects in the areas of bone marrow transplantation, immunology and immunotherapy, normal and malignant hematopoiesis, human immunogenetics, molecular pharmacology, molecular biology and gene therapy, as well as other programs, are available. The aim of the projects will be to contribute new and useful information relevant to pediatric oncology and to develop the research capabilities of the trainees to allow them to establish themselves as independent investigators. Physicians who have completed three years of training as residents in pediatrics will be eligible. Those most qualified and motivated to enter into investigative endeavors will be selected. In the past, many of the applicants have had previous laboratory experience. Of the eleven trainees supported by this NRSA who have completed their training since the last competitive renewal, ten have remained in academic pediatric oncology. The applicants are requesting funding for two postdoctoral fellowships per year in a two-year program (a total of four positions). This program involves the laboratory and clinical research facilities of the Fred Hutchinson Cancer Research Center and the University of Washington; the clinical facilities of the Division of Hematology-Oncology at the Children's Hospital and Medical Center, the primary clinical pediatric service of the University of Washington; and the clinical facilities of the pediatric oncology service of the Fred Hutchinson Cancer Research Center.