Lahey was executive vice president of Marist College, where he served as chief operating officer. He became Quinnipiac’s president in 1987. Upon his arrival, Lahey initiated a strategic planning process, leading to the University’s unprecedented growth over the past two decades in enrollment, academic programs, reputation and physical plant.
Lahey is a director of the United Illuminating Company, the Aristotle Corporation, the Yale New Haven Hospital, and the Alliance for Gene Cancer Therapy.
He is a member of the Council of the American Bar Association Section of Legal Education and Admissions to the Bar. As vice-chairman of the New York City St. Patrick’s Day Parade Committee, he has devoted much of his time to educating the public about the historic implications of Ireland’s Great Hunger. In 1997, Lahey served as Grand Marshal of the Saint Patrick's Day Parade in New York City.[2] In 2011, Lahey was named Irish American of the Year by Irish America magazine.[5]
Lahey announced his retirement at the end of the 2017–2018 fiscal year at Quinnipiac University. At the time of his retirement, he had served Quinnipiac as president for 31 years and 3 months, watching the student body grow from 1,902 students to roughly 10,000. He was succeeded on July 1, 2018 by Judy Olian.