Abstract The major goal of this training program, which entered its 45th year in September 2019, is to successfully train young investigators in a career in biomedical research pertaining to lymphocyte biology, ranging from cancer immunotherapy to neoplastic transformation. This competitive application is especially timely given that results from Penn-based immunotherapy trials were markedly effective in treating leukemia, a result that contributed to two FDA-approved drugs. The Penn training program sits at the nexus of the NCI-designated Abramson Cancer Center and the Institute for Immunology to offer multi-disciplinary training in both basic and translational research related to cancer immunobiology. Drs. Pear (Program Director) and Beatty (Program Co- Director) will provide the sustained leadership required for continued development of top-tier cancer immunobiology training at Penn and have an administrative structure that oversees the needs of the training program, assisted by an Internal Executive Committee and an External Advisory Board and complemented by individual research trainee advisory committees. Our training faculty are in multiple departments campus-wide, including the University of Pennsylvania School of Medicine, School of Veterinary Medicine, Children's Hospital of Philadelphia and the Wistar Institute, and have diverse interests that are focused on cancer immunobiology. Common among our trainers is successful mentoring, independent funding, continued productivity and projects relevant to cancer immunobiology. Our 2 predoctoral and 8 postdoctoral trainees are competitively selected and are expected to meet high standards of competence, motivation and perseverance, and have a commitment to a research career in cancer immunobiology. Recruitment of qualified trainees from diverse backgrounds is high priority. The training program is anchored in an intensive laboratory experience with a rigorous mentor. The laboratory experience is complemented by basic lecture courses in immunology and related disciplines, advanced seminar courses in various aspects of cancer immunobiology, cancer biology and bioethics, seminars from visiting scientists and Penn faculty, research conferences, workshops and retreats. Programs developed specifically for our trainees include , a monthly research-in-progress meeting, a tumor immunobiology journal club, clinical connection experiences, an annual retreat and special symposia, and training in the responsible conduct of research. Ultimately we will continue to meet our twin goals of supporting the research and training of young scientists with new or established interests in cancer immunobiology and providing a rich and rigorous training environment in cancer immunobiology that provides multi-disciplinary training in cancer biology and immunology.