Thomas Ehrlich was born on March 4, 1934 in Cambridge, Massachusetts. He and his wife, Ellen Rome Ehrlich had three children, David, Elizabeth, and Paul. He earned his A.B. from Harvard College, graduating magna cum laude in 1956. He then went on to earn his LL.B. from Harvard Law School, graduating magna cum laude in 1959.

Prior to his appointment at Indiana University, Ehrlich held several positions. From 1959-1960 he worked as a law clerk for the U.S. Court of Appeals for the Second Circuit in New York City. He then worked from 1960-1962 as an associate for Foley, Sammond & Lardner in Milwaukee, Wisconsin. From 1962-1965 Ehrlich worked at the Department of State as a Special Assistant to the Legal Advisor, and from 1964-1965 as the Special Assistant to the Undersecretary of State followed by a tenure as professor and Dean of the Stanford University Law School. From 1976-1979 he served as president of Legal Services Corporation in Washington, D.C. Then in 1979 he was appointed director of the International Development Cooperation Agency by then President Jimmy Carter. During the year of 1980 he was a guest scholar at The Brookings Institution. From 1982-1987 he served as provost and professor of law at the University of Pennsylvania.

Ehrlich accepted an appointment at Indiana University and began his presidency on August 1, 1987. During his time at IU, he was also held the rank of professor of law and repeatedly taught undergraduate ethics courses and law courses. In 1991, Ehrlich was appointed to the board of directors of the Commission on National and Community Service by President George H.W. Bush. Student enrollment grew under his tenure but he, and other Indiana college and university presidents, faced many challenges with the state legislature to secure state funding.

Ehrlich announced his retirement in August of 1993, saying that he would remain at IU through the 1993-1994 school year. In his announcement, he cited his desire to return to full-time teaching and research, and also to be able to spend more time with his children and grandchild in California. After his presidential duties at IU ended, Ehrlich spent a semester teaching at Duke University's Terry Stanford Institute of Public Policy before moving to California. He then became Distinguished University Scholar at California State University and an adjunct professor at Stanford Law School. In 2000, IU established an annual Thomas Ehrlich Award, to be presented to a faculty member from one of the eight IU campuses on Founder's Day.

Ehrlich received five honorary degrees, including degrees from Villanova University in 1979, Notre Dame in 1980, and the University of Pennsylvania in 1987. He has been an author, co-author, or editor of fourteen books, including The Courage to Inquire(1995),Service-Learning in Higher Education: Concepts and Practices(1996), andEducating for Democracy: Preparing Undergraduates for Lives of Responsible Political Engagement (2007).