John Foster Furcolo was born in New Haven, Connecticut, on July 29, 1911. His father, Charles Furcolo, was an Italian immigrant and a doctor, and his mother was an Irish immigrant. Furcolo attended public schools in Longmeadow, Massachusetts and New Haven. He then attended Yale University, where he graduated in 1933, and finally Yale Law School, where he received his LL.B. in 1936. At Yale he played a variety of sports, serving on both the boxing team (as a welterweight) and the baseball team. According to his brother Charles, he played second base. He was undefeated as a boxer and was encouraged to turn professional, but chose not to. He also engaged in literary pursuits, writing short stories and plays that were produced locally. Furcolo dropped use of his first name when he entered politics.