In 1960, Hicks won election to Boston's school board, where she served until 1970, including holding the position of chairwoman from 1963 to 1965. During her tenure on the school committee, she came into conflict with civil rights groups and black residents of Boston over her opposition to plans to integrate schools by busing students between districts to achieve racial balance. From 1970 to 1971, she served on the Boston City Council. In 1970, she won the Democratic nomination for the U.S. House seat of the retiring John McCormack. She went on to win the general election and serve one term, 1971 to 1973. In 1971, she was an unsuccessful candidate for mayor of Boston. She was defeated for reelection to Congress in 1972 by Joe Moakley, a Democrat who ran as an independent.