Born in Cambridge, Massachusetts, Regan earned his bachelor's degree in English from Harvard University in 1940 and then joined the United States Marine Corps at the outset of World War II reaching the rank of lieutenant colonel. He served in the Pacific theater and was involved in five major campaigns, including Guadalcanal and Okinawa. After the War, he joined Merrill Lynch & Co., Inc in 1946 as an account executive trainee, working up through the ranks, eventually taking over as Merrill Lynch's chairman and CEO in 1971, the year the company went public. He held those titles until 1980.
President Ronald Reagan selected Regan in 1981 to serve as Treasury secretary, becoming a spokesman for supply-side economics (also called Reaganomics). He helped engineer tax reform, reduce income tax rates and ease the tax burden on corporations. Regan unexpectedly switched jobs with then White House Chief of Staff James Baker in 1985, a position he kept until 1987, when he was pressured to resign for his involvement with Iran-Contra. As Chief of Staff, Regan was very involved in the day to day management of a lot of White House policy, which led Baker to give a stinging rebuke that Regan was becoming a "Prime Minister" inside an increasingly complex Imperial Presidency.
Regan's book, For the Record: From Wall Street to Washington (ISBN 0151639663), exposes his disagreements with First Lady Nancy Reagan including claims that Nancy's personal astrologer, Joan Quigley, helped steer the President's speaking decisions.
Regan retired quietly in Virginia with Ann Buchanan Regan, his wife of over sixty years. Late in life, he spent nearly ten hours a day in his art studio painting landscapes, some of which sold for thousands of dollars and hang in museums. Regan had four children and nine grandchildren.