Informatics has become a major theme and methodology for biomedical science, health care delivery, and public health. Biomedical informatics involves modeling and understanding the cognitive, information processing and communication tasks of biomedical science, medical practice, education and research. The field is inherently interdisciplinary, drawing on traditional biomedical disciplines, the science and technology of computing, biostatistics, epidemiology, decision sciences, and health care policy and management. There is a common core of knowledge, skills, and experiences that all trainees need to have to equip them to engage meaningfully in the field. The Master of Medical Sciences in Biomedical Informatics at Harvard Medical School is a two-year post-doctoral degree program. The MMSc in Biomedical Informatics consists of didactic course work, a seminar series, and a mentored research project. Our program is open to federally funded post-doctoral fellows at Harvard and its affiliated hospitals. Each student chooses from one of four possible tracks: Bioinformatics, Clinical Informatics, Imaging Informatics, and Population Health Informatics. A written thesis and an oral presentation and defense of the thesis is required.