PROJECT SUMMARY / ABSTRACT This is a new application seeking support for the training program in hematology-oncology in the Department of Pediatrics at Washington University School of Medicine. This program had been continuously funded between 1999 and 2020. We have extensively redesigned the program to enhance its flexibility in order to keep pace with the changing landscape of biomedical science. The long-term goal is to produce independent investigators capable of making important contributions to our field. The program is open to MD’s or MD/PhD’s and will support one second-year (PGY-4) and one third-year fellow (PGY-5) each year. The trainees will be recruited from the extensive network of pediatric subspecialty training programs at The at Washington University School of Medicine. The fellowship program is comprised of three to four years of training, only two of which will be supported by the T32. The Hematology-Oncology fellowship includes many qualified applicants with backgrounds in hematology and oncology research. Only those applicants with the highest likelihood of success as physicians/scientists will be chosen for funding. Support decisions will be made by the program leaders. Supported trainees will participate in didactic seminars, lectures and journal clubs that cover genomics, epigenomics, developmental biology, cellular therapeutics, clinical trial design and performance, and survivorship as appropriate to their research projects. Trainees may perform their postdoctoral research in a wide range of laboratory and clinical settings at Washington University, provided the research is relevant to the field of pediatric hematology-oncology. Training will be overseen by a program steering committee with expertise in each of these domains. Drs. Joshua B. Rubin, MD, PhD and Jorge Di Paola MD, PhD will serve as Program Directors and Dr. Laura Schuettpelz, MD, PhD will serve as the Training Director. Support for this of program will provide trainees with the opportunity to leverage the prodigious strengths of the Washington University research and clinical enterprises, in their quests to become the next generation of leaders in pediatric hematology-oncology research.