Barlett was born in DuBois, Pennsylvania, on July 17, 1936, and he grew up in Johnstown, Pennsylvania. He attended Pennsylvania State University and served three years as a special agent with the United States Army Counter Intelligence Corps. Barlett began his journalism career in 1956 as a general assignment reporter at the Reading (Pennsylvania) Times, and later held a similar position at the Akron (Ohio) Beacon Journal. In 1965, he began working as a full-time investigative reporter at the Cleveland Plain Dealer, and subsequently moved to similar positions at the Chicago Daily News and The Philadelphia Inquirer before joining Time in 1997. In 2006, he became a contributing editor of Vanity Fair. Barlett is married and has a son and a stepson.