Project Summary Despite progress in prevention and treatment by sanitation, antimicrobials, vaccines, and other measures, infectious diseases still threaten life and health. In 2016, communicable diseases accounted for over 17% of disability-adjusted life years lost worldwide. With globalization, infectious disease threats (previously seen as being limited to less-developed countries) threaten everyone (like Ebola, HIV, MERS, pandemic influenza, and growing resistance to antimicrobial drugs). The combination of computational power and “Big Data” provides a new opportunity to study infectious diseases and their transmission through novel approaches, necessitating new sophistication in the training of infectious disease epidemiologists. We recognize the need for a corps of academic and government epidemiologists, equipped to deploy sophisticated approaches to causal inference, transmission-dynamic modeling, model fitting using MCMC and other Bayesian techniques, population genomics, phylogenetics, and other novel techniques. The goal of Harvard Chan School of Public Health’s (HSPH) Interdisciplinary Program in Infectious Disease Epidemiology (IPIDE) is to train graduates who can apply these diverse tools to meet the infectious disease threats of a new generation. Our training faculty includes leading practitioners of all of these techniques and our recent graduates are emerging with deep training, research experience, and publications in many of these areas. The training program includes coursework in epidemiology, drug resistance, and mathematical modeling of disease from IPIDE under the close supervision of our 25 faculty mentors, leading either to a DSc or a PhD. A tremendously successful postdoctoral training program has to date relied on research funding. Harvard’s IPIDE has been running successfully for 20 years, and this training grant has helped develop not only a new cadre of students with the capacity to monitor, prevent, and suppress diverse emerging infectious diseases but has also allowed IPIDE to expand its faculty, funding, diversity of research, and, the number of students who join the infectious disease epidemiology program. Over the past ten years, 23 trainees have been supported, 18 graduated, and they published 581 peer-reviewed manuscripts (177 first author publications). For the current submission, we propose to support 5 pre-doc and 2 post-doctoral trainees each year over the next five-year project period. Adding these postdoctoral positions will realize synergies and collaborative opportunities between pre- and postdoctoral fellows and create the opportunity to build new means of integrating postdocs into the highly interdisciplinary training environment.