Born in Geneva, Ohio in 1945 as Gail Gleason, Collins has a B.A. in journalism from Marquette University and an M.A. in government from the University of Massachusetts Amherst. She wrote for Connecticut publications like the Hartford Advocate and, in 1972, founded the Connecticut State News Bureau, a news service providing coverage of the state capital and Connecticut politics; when she sold it in 1977, it had grown into the largest service of its kind in the United States. Collins later wrote as a columnist for the New York Daily News, Newsday, and the Connecticut Business Journal, as a financial reporter for United Press International, and as a public affairs host for Connecticut Public Television.

Collins joined The New York Times in 1995 as a member of the editorial board, and later as an op-ed columnist. In 2001, she was named the paper's first female Editorial Page Editor, a position she held for six years. She resigned from this post at the beginning of 2007 to take a six-month leave to focus on writing her book When Everything Changed: The Amazing Journey of American Women from 1960 to the Present, returning to the Times as a regular columnist in July 2007.

Beyond her work as a journalist, Collins has published several books: The Millennium Book, which she co-authored with her husband, CBS News producer Dan Collins; Scorpion Tongues: Gossip, Celebrity and American Politics; America's Women: Four Hundred Years of Dolls, Drudges, Helpmates, and Heroines; and the aforementioned When Everything Changed.

Collins has also taught journalism at Southern Connecticut State University and, as of Fall 2009, Collins co-teaches (with Seth Lipsky) an opinion writing course in Columbia University's Graduate School of Journalism .