This proposal requests funding for years 16-20 of the UCSF Biology of Infectious Diseases Training Program to train physician-scientists in infectious diseases translational research, both clinical and laboratory-based, for research-intensive or research-related careers in academia, industry, and the public health sector. Funding is requested for four postdoctoral trainees per year, MDs or MDs with dual degrees, recruited from the UCSF Adult Infectious Diseases and the Pediatrics Infectious Diseases Fellowship Programs. This training program is designed to provide flexible but rigorous protected research training in relevant laboratory-based, translational, and clinical research in the areas of epidemiology, public health, global health, HIV/AIDS, genomics, antimicrobial resistance, microbial pathogenesis and host response, and immunology. The 31 faculty are drawn from 6 participating departments from the UCSF School of Medicine (Adult Infectious Diseases, Biochemistry and Biophysics, Epidemiology and Biostatistics, Experimental Medicine, Microbiology and Immunology, Pediatric Infectious Diseases) and the University of California, Berkeley School of Public Health Division of Infectious Diseases and Vaccinology. Participating faculty have been selected on the basis of research area and expertise, funding, productivity, and proven success in training and mentoring post- doctoral fellows. Each fellow will undertake an in-depth research project supervised by one or more of the participating faculty. Emphasis is placed on personalized training and instruction. The educational program provides for special courses, small group conferences, research conferences and seminars, coursework in immunology, microbial pathogenesis, biostatistics, epidemiology, study design, scientific writing, and responsible conduct of research. The quality and effectiveness of the program is measured by the success of trainees in completion of fellowship training, the number and quality of publications in peer-reviewed journals and research presentations, obtaining research funding (e.g., independent research awards, K-awards or equivalent career-development awards, R01-level or equivalent awards), and attainment of a research-oriented career as medical school faculty, in industry, or in the public health sector. The career development component continues to be strengthened through a process of regular and rigorous review and feedback of progress and performance to assure that trainees achieve their career goals. Of the 42 fellows supported by the training program since 2000, 35 (83%) are still in health-related careers, underscoring the extraordinary success of our training program. Funding is requested to continue this highly successful program.