Dr. Mastrangelo grew up in Boston, attending Boston University. He served in the U.S. Air Force during World War II. He was awarded the Air Medal, Bronze Star and Presidential Unit Citation. He worked at Stamford Hospital from 1941 to 2001 as chief of the anesthesiology department, chairman of the medical board, president of the medical staff, vice chairman of the board of directors of the hospital and vice chairman of the board of Stamford Hospital Corp. and Stamford Hospital Foundation.
Dr. Angelo Mastrangelo, Jr. was named the Citizen of the Year because of his tireless advocacy for better health care for the citizens of Stamford. He raised more than $10 million for projects and endowments throughout his career. Dr. Mastrangelo organized the first Poison Control Center in Connecticut, was a chairman of Stamford Hospice and member of the Stamford AIDS task force. He led the campaign of the United Fund of Stamford and became a member of the United Way board of Directors. He was also chair of the Stamford Health Commission, the Center for Continuing Care of Greater Stamford and the Tandet Center for Continuing Care. He was awarded the Stamford Advocate Community Leader of the Year in 1992. The following year the New England Association of Health Care Philanthropy honored him with the Distinguished Service Award. He also received the Stamford Festival of the Arts Award at that time.