Kate Gilbreth Baker (Bonnie Hunt) narrates her story about her large family: her husband, Tom (Steve Martin), is a football coach at a small rural college in Midland, Michigan, where he raised twelve children. Kate has written her story in a book and hopes to send it to her friend to publish the book. Life at the Midland house is almost perfect for the Bakers until Tom unexpectedly receives an offer from his old friend and football teammate, Shake McGuire (Richard Jenkins), to coach at his alma mater in his hometown of Evanston, Illinois. Since Tom was raised in Evanston and the football team he accepts the offer, which disappoints nearly all the children. Tom demands all the children to vote on moving, but despite losing it, he has the entire family to return to Evanston for a better home and space. The family's second child, Charlie (Tom Welling), refuses to leave his girlfriend, Beth (Tiffany Dupont), and the others simply don't want to leave their friends and home. Despite being given a fancy white mansion as a home by Shake for their move, the atmosphere at the Bakers' new house, which is absolutely huge, is tense and the situation at school is even worse. In general, the younger children are harassed at school. Charlie is taunted for being a country boy, while the family's sixth and seventh children, Jake and Mark (Jacob Smith and Forrest Landis), are consistently antagonized by a bully named Quinn (Cody Linley), the twins of the bunch Kyle and Nigel (Brent and Shane Kinsman), begin to cause trouble at school and the Bakers' new neighbors, Tina and Bill Shenk (Paula Marshall and Alan Ruck), are very over-protective of their son and only child, Dylan (Steven Anthony Lawrence), and does not want him to play with the younger kids. Dylan visits the Bakers when he gets into a game of hockey with his friends indoors, which leads to Dylan and Tom hanging on the chandelier and breaks off and smashes on the floor below.When her book is ready to pick up for publication, Kate is required to do a national book tour to promote it and will not be back home until the book tour is completed. Tom thinks that he can handle everything in the family's household while Kate is away, so he decides to hire the family's oldest child, Nora (Piper Perabo), and her self-absorbed teenage boyfriend, Hank (Ashton Kutcher), to manage the younger children. However, Hank is reluctant since the younger children have attacked him earlier by setting his pants on fire, but he agrees after falling under Nora's begs. When Nora and Hank arrive, the younger children plan to make Hank the target of their latest antagonistic prank by soaking his underwear in meat and letting the family's pet dog, Gunner, attack Hank by chewing his bottom, prompting him to refuse to assist in baby-sitting. As a result, Nora is angry at the younger children and drives off with Hank, while Tom berates them for their prank and cuts off their allowance for a month.After Kate departs for her book tour, Tom realizes that he cannot handle the younger children on his own after a chaotic night where the house becomes a rampaging stampede during the chores they perform. In reply to this revelation, Tom tries to hire a housekeeper, but nobody is willing to work with a family as large as the Bakers, so Tom decides to bring all of the football players from work into the family's house for game practicing in the living room in order to prepare for the Saturday night football game as the younger children perform chores and their household games. However, the younger children start causing trouble at school when Kyle and Nigel hurt their kindergarten teacher and the others burst in fury and stand up against the bullies by fighting them. When Tom gets complaints about those incidents, he grounds the younger children from any fun and games and forbids them from going to Dylan's birthday party, despite the fact that they already have presents for him. Without Tom noticing them, the younger children suddenly sneak out of the house and head to the party to start chaos. While Tom is teaching the football players how to win and participate for the Saturday night football game, they notice the guests running out of Dylan's house as one of the children's gifts inside was a snake scaring them away. Tom and the football players decide to investigate the chaos. After the football players successfully capture all the younger children, Tom tries to capture the family's fifth child, Sarah (Alyson Stoner), in the bounce house, but during the mess, a helium tank suddenly jams the air in the bounce house, causing it to inflate and explode. Tom accidentally falls on Dylan, in which he ends up in the hospital. Tina forbids the kids from playing with Dylan, while Shake warns Tom not to bring all the football players to his house or the kids to the department anymore, causing Tom to cancel the entire Saturday night football game.Meanwhile, Kate hears from the younger children about the chaos and cancels the book tour to take charge of the situation. Kate's publisher decides to create an additional promotion for her book by inviting Oprah Winfrey to tape a segment about the Bakers in their home. Despite much coaching from Kate, and Kate being furious at Tom for not telling her that he could not handle it, the Bakers aren't able to demonstrate the loving, strongly bonded family that Kate described in her book. When Mark becomes upset that his pet frog, Beans, has died, in which Sarah rudely tells him that nobody cares, a heated fight erupts before the segment starts, leading the cameramen to call Winfrey to cancel it. As a result of the fight, Mark feels unwanted and runs away from home, prompting the Bakers to hold their search party to find him. Meanwhile, Nora dumps Hank when he is more focused with watching himself on television instead of searching for Mark. The Bakers call the police, their close friends, and Dylan to join in the search for Mark. However, the Bakers cannot find Mark until Tom indulges a hunch that Mark is attempting to run back to the Bakers' old home, and eventually finds Mark on an Amtrak train departing from Chicago to Midland. Reuniting with the rest of their family, the Bakers realize that they have not been a close family and they begin to address their issues with each other. Tom ultimately resigns from his position at his alma mater with Shake and finally settles for a less time-consuming job. The film ends when Kate narrates that the Bakers are closer as a result of their experiences and Tom's decision to love his family more than his job. When Christmas arrives, the Bakers have a massive dinner when the new chandelier in the lobby snaps off and crashes once again.
- Kanga, Roo, Lumpy, Ash and his friends, Littlefoot and his friends, BrerRabbit, Dr. Alan Grant and his friends, Ronald McDonald and his friends, Chipmunks Tunes Babies & All-Stars' Adventures team, Elina and Bibble (from Barbie Fairytopia), the Bratz Babyz, Mickey Mouse, Donald Duck, Goofy, Bugs Bunny, Daffy Duck, Road Runner, Wile E. Coyote, Team Rocket, Scar, the hyenas, Arthur, Cecil, the Predator, Ozzy, Strut, Ichy and Dil Guest Stars In This Film
- This is an NTSC film with NTSC bits from the Cartoon All-Stars movies and more!