The prevalence of pediatric allergic, immunological and rheumatologic disorders has been steadily increasing with more than 15% of children now affected. However, the number of physicians trained to treat children with these conditions as well as to investigate the genetics, pathogenesis and innovative approaches to therapy of these disorders remains disproportionately small. In addition, the role of the immune response in modulating the clinical course of infectious disease is coming into sharp focus with the COVID-19 pandemic. There is a great need both to advance understanding of the basic immunobiology underlying these conditions and to generate a highly qualified workforce of investigators who will do this work. Recent advances in understanding of the immune system, along with the emergence of powerful yet complex research technologies in molecular biology, transcriptomics, metabolomics, human genetics, epigenetics, structural biology, cell biology and immunology have not only created fertile ground for advancement of understanding of immunological mechanisms but have made it essential for trainees to develop understanding of and experience in these approaches. Such training will prepare MD and PhD scientists to advance our knowledge through basic research, clinical investigation and the implementation of novel therapeutic strategies. Equally important, it will generate a cadre of physician scientists ready to train the next generation of investigators. The proposed training program will recruit a diverse group of the most talented and committed young pediatric physician scientists as well as PhD’s (all postdoctoral) committed to clinically relevant immunology research and will provide them with an intensive training experience in research in an unparalleled environment. In the year prior to enrollment in the program, physicians will receive one year of clinical training (not funded by this grant). All training will be within the general discipline of Immunology, with a broad representation of immunological disorders (including asthma, food allergy, atopic dermatitis, primary immune deficiency syndromes, systemic lupus erythematosus, Kawasaki disease) and basic immunological mechanisms (such as tolerance, immunogenomics, epigenetics, innate immunity, cellular immunology and immune responses to SARS-CoV-2) covered by an internationally recognized faculty in the Harvard Medical School community. A three-year training experience is proposed for 9 trainees per year, each with MD, MD-PhD or PhD credentials.