Costner had a typical middle class upbringing in California, where his father worked for the electric utility and his mother worked at the state welfare department. As a college senior at Cal State Fullerton he was rejected for a role in the school’s production of "Rumpelstiltskin." He was considered something of a joke in Hollywood after he was edited out of his first major role in "The Big Chill".

He married his college sweetheart, Cindy Silva, in 1978; they divorced in 1994. He has three children from that marriage and a fourth child from another relationship. He hoped at one time to become a professional baseball player – that may account for the fact that several of his movies are centered around the sport.