In 1988, Dottie Hinson (Geena Davis) attends the opening of the new All-American Girls Professional Baseball League (AAGPBL) exhibit at the Baseball Hall of Fame. She sees many of her former teammates and friends, prompting a flashback to 1943.
When World War II threatens to shut down Major League Baseball, candy magnate and Cubs owner Walter Harvey (Garry Marshall) persuades his fellow owners to bankroll a women's league. Ira Lowenstein (David Strathairn) is put in charge, and Ernie Capadino (Jon Lovitz) is sent out to recruit players. Capadino attends an industrial-league softball game in rural Oregon and likes what he sees in Dottie, the catcher for a local dairy's team. Dottie turns down Capadino's offer, happy with her simple farm life while waiting for her husband Bob (Bill Pullman) to come back from the war. Her sister (and teammate) Kit (Lori Petty), however, is desperate to get away and make something of herself. Capadino is not impressed by Kit's hitting performance, but agrees to take her along if she can change Dottie's mind. Dottie agrees, but only for her sister's sake.
Dottie and Kit head out to Harvey Field in Chicago for the tryout. There they meet a pair of New Yorkers, taxi dancer "All the Way" Mae Mordabito (Madonna) and her best friend, bouncer Doris Murphy (Rosie O'Donnell), along with soft-spoken right fielder Evelyn Gardner (Bitty Schram), illiterate, shy left fielder Shirley Baker (Ann Cusack), pitcher/shortstop and former Miss Georgia beauty queen Ellen Sue Gotlander (Freddie Simpson), gentle left field/relief pitcher Betty "Spaghetti" Horn (Tracy Reiner), homely second baseman Marla Hooch (Megan Cavanagh), who was discovered by Ernie, Dottie and Kit in Fort Collins, Colorado playing for her father's American Legion team, and first baseman Helen Haley (Anne Ramsay), a native of Saskatchewan. They and eight others are selected to form the Rockford Peaches, while 48 others are split among the Racine Belles, Kenosha Comets, and South Bend Blue Sox.
The Peaches are managed by Jimmy Dugan (Tom Hanks), a former marquee Cubs slugger who initially treats the whole thing as a joke. The league attracts little interest at first. With a Life magazine photographer in the stands, Lowenstein begs the players to do something spectacular. Dottie obliges when a ball is popped up behind home plate, catching it while doing a split. The resulting photograph makes the magazine cover. A publicity campaign draws more people to the ballgames, but the owners remain unconvinced. Due to Kit's sibling rivalry with her sister, she is traded to the Peaches' rival, the Racine Belles.
The Peaches end the season qualifying for the league's World Series. While the Peaches were in their locker room, Jimmy gives Betty a telegram that informed her about her husband George being killed in action while fighting in the Pacific Theater. With the sudden loss and heavy grief, Betty leaves the team. Later that evening, Dottie receives a surprise when Bob, who has been serving in Italy with the 36th Infantry Division, shows up. He has been discharged from the Army. The following morning, Jimmy discovers that Dottie is going home with Bob. He is unable to persuade her to at least play in the World Series; he tells her she will regret her decision.
The Peaches and Belles meet in the World Series, which reaches a seventh and deciding game. Dottie, having reconsidered on the drive back to Oregon, is the catcher for the Peaches, while Kit is the starting pitcher for the Belles. With the Belles leading by a run in the top of the ninth, Dottie drives in the go-ahead run. Kit is the final batter. Under immense pressure, she gets a hit and, ignoring the third base coach's sign to stop, scores the winning run by knocking her sister over at the plate and dislodging the ball from Dottie's hand. The sellout crowd convinces Harvey to give Lowenstein the owners' support. After the game, the sisters reconcile before Dottie leaves.
Back in the present, Dottie is reunited with several other players, including Kit, whom she has not seen in several years. The fates of several of the characters are revealed: Jimmy, Bob, and Evelyn have died, while Marla has been married to Nelson, a man she met in a bar, for over 40 years. The original Peaches sing a team song composed by Evelyn and pose for a group photo.
At the Baseball Hall of Fame, Dottie Hinson has a flashback to what year?
1943