Professor Guttag received a bachelor's degree in English from Brown University in 1971, and a master's degree in applied mathematics from Brown in 1972. In 1975, he received a doctorate in computer science from the University of Toronto. He was a member of the faculty at the University of Southern California from 1975-1978, and joined the MIT faculty in 1979.

From 1993 to 1998, Professor Guttag served as Associate Department Head for Computer Science of MIT's Electrical Engineering and Computer Science Department. From January of 1999 through August of 2004, Professor Guttag served as Head of that department. EECS, with approximately 1800 students and 125 faculty members, is the largest (and, of course, best) department at MIT.

Professor Guttag also co-heads the MIT Computer Science and Artificial Intelligence Laboratory's Networks and Mobile Systems Group. This group studies issues related to computer networks, applications of networked and mobile systems, and advanced software-based medical instrumentation and decision systems. Professor Guttag has also done research, published, and lectured in the areas of software defined radios, software engineering, mechanical theorem proving, and hardware verification.

Professor Guttag currently serves on the technical advisory board of Vanu, Inc., on the Board of Directors of Empirix, and on the Board of Trustees of the MGH Institute of Health Professions. He is also a Fellow of the ACM and a member of the American Academy of Arts and Sciences.