Denis Leary was born and raised in Worcester, Massachusetts, the son of Nora and John Leary, Irish immigrants who had grown up together. After a childhood in the 1960s, Leary went to Emerson College in Boston, where he tried his hand at acting and writing. He was a charter member of Emerson's Comedy Workshop, and taught at the college for five years after graduating. By that point he had written several pieces for magazines and had worked at stand-up comedy for a time. In 1990 he and his wife Ann flew to London to perform in the BBC's Paramount City.