This is a competing renewal of a postdoctoral training program entitled "Training in Investigative Infectious Diseases" based in the Section of Infectious Diseases, Department of Internal Medicine at the Yale School of Medicine. The aims of this training program are to: (a) develop the next generation of Infectious Disease (ID) investigators trained in basic, clinical, and/or translational research (b) develop new insights into infectious diseases of national and international significance (c) advance the principles associated with high quality research including adherence to ethical principles and (d) increase diversity among ID physician-investigators. The program is designed for physicians with an MD, MD PhD, DO or equivalent. Most trainees will be Fellows in Infectious Diseases, but selected MDs or MD-PhDs with clinical training in other fields will also be eligible to participate. The highly accomplished training faculty has four broadly defined areas of research: (1) Innate Immunity and Microbes, (2) Vector-borne Diseases, (3) Molecular and Human Infectious Disease Pathogenesis, and (4) Clinical and Epidemiologic Infectious Disease Research. Detailed plans for trainee admission to the program, mentor and mentorship committee selection, and evaluation of trainee progress are in place. In addition to outstanding research training, Yale has opportunities for study toward advanced degrees such as a Masters in Health Science or Masters of Science with a concentration in Epidemiology of Infectious Diseases or PhD in Investigative Medicine that are open to physicians in the T32 training program. Extensive didactic training is also available through the Graduate School of Arts and Sciences, School of Public Health and the Yale National Clinician Scholars Program and includes required training in rigorous experimental design, statistical methods, grant writing and the responsible conduct of research. This combination of outstanding research opportunities, didactic coursework and seminar series, and career development training in grant writing and presentation skills has resulted in a high level of programmatic success in training physician-investigators at Yale who choose research careers in academia or industry. At the same time, the T32 Infectious Diseases training program at Yale continues to evolve and improve, with the addition of new training faculty with interests in global health, enhanced recruitment of MD-PhD physician-scientists in part through recruitment from the Physician-Scientist Track of the Yale Internal Medicine Residency Program, a plan to enhance the number of trainees who are members of groups underrepresented in medicine (URiM) that leverages a critical nucleus of URiM fellows and faculty, and new initiatives such as a research and career development retreat. We believe these changes will further enhance the ability of graduates of the program to contribute to high impact, new knowledge in Infectious Disease research.