With a partner, Grousbeck founded Continental Cablevision (later Media One) in 1964. He was President of that company through 1980, and Chairman through 1985. He was a Visiting Lecturer and then Lecturer at Harvard Business School from 1981-85. He became a Visiting Lecturer at Stanford in 1985, a Lecturer in 1986, and a Consulting Professor in 1996.
Grousbeck has served on numerous for-profit and not-for-profit Boards over the past 37 years, including (currently) Alta Colleges, Asurion Corp., ResponseLink, and the Boston Celtics. He was a Trustee of the William and Flora Hewlett Foundation, Vice Chairman of the Massachusetts Board of Higher Education, Chairman and President of Newton-Wellesley Hospital, Chairman of the Board of Sponsors of New England Eye Bank, Overseer of Children’s Hospital (Boston), and Chairman of Menlo School and College. He is the principal owner of the Boston Celtics.
He holds an MBA from Harvard University, and Bachelor of Arts and Doctor of Humane Letters (Hon.) degrees from Amherst College.