Plot summary

College football coach Tom Baker (Steve Martin) has raised twelve children (Nora (Piper Perabo), Charlie (Tom Welling), Lorraine (Hilary Duff), Henry (Kevin G. Schmidt), Sarah (Alyson Stoner), Jake (Jacob Smith), Mark (Forrest Landis), Jessica (Liliana Mumy), Kim (Morgan York), Mike (Blake Woodruff), Kyle (Brent Kinsman), and Nigel (Shane Kinsman)) in Midland, Illinois. TOm teaches 12 games every yr at the local college and they empty their accounts 12 times each yr to make ends meet. His wife, Kate (Bonnie Hunt), has written their life story in a book, which she hopes to publish. Tom had 7 brothers and sisters and Kate lost her sister and wished she had a large family. They met at the Illinois Polytechnic Univ. He wanted to be a football coach and she a sports reporter. She knew he was the one, after an hour. After 3 kids, they decided that having a large family was more important than their career. So, they moved to Midland and bought a large house, and sacrificed their city careers to raise a big family. After 10 kids, Tom got a vasectomy, but he did hear the doctor say that the procedure wont be effective for a few weeks, and they had twins 9 months later.Charlie is a teenager and a shoe in for the football scholarship. Marj is silent brooding one. Nora is dating Hank and moving in with him. Mark has a bullfrog that creates chaos at the breakfast table. He is outcast in the family and is told that the FedEx guy dropped him off as he doesn't fit into the family. Tom accepts an offer from his friend and colleague Shake McGuire (Richard Jenkins) to coach at his Alma mater (Illinois Polytech) in his hometown of Evanston (fat 5 yr contract, housing allowance, moving expenses and free school for the kids), even though the kids are against it and unwilling to leave their friends. Tom argues that this is his dream job and wants his family to support him. The atmosphere at the Bakers' new house quickly becomes tense, and Charlie and Mark are bullied at their respective schools. Tina (Paula Marshall) and Bill Shenk (Alan Ruck), the Baker family's new neighbors. Dylan Shenk (Steven Anthony Lawrence), Tina and Bill's son. On their first visit, Dylan ends up playing hockey with the kids and ends up swinging from the chandelier. Tom saves Dyland and that's the most fun Dylan had in his life. Tom gifts Charlie an old car, so he can visit his girlfriend Beth (Tiffany Dupont) in Midland. Mark takes a room in the attic and finds hidden passageways in the house where he can hide and snoop on everyone in the house.Kate embarks on a national book tour to promote her newly published book. Tom has Nora and her self-absorbed model/actor boyfriend, Hank (Ashton Kutcher), help look after the other children. Disliking Hank and realizing that he hates kids (the last time Hank visited, the kids set his pants on fire), the children trip him into their pool of dirty water and, while he showers, soak his underwear in raw meat. At lunch, the children unleash their dog, Gunner, onto him. Hank and Nora angrily leave, and Tom punishes the younger children by cutting off their allowances.After a chaotic night (One of the kids was hit by a dart, 2 kids puke looking at the blood, one kid slides into the puke, one kid has a bucket stuck to their head), Tom realizes he cannot handle the children on his own. Meanwhile Kate informs TOm that she has to stay a few extra days to finish her book tour. Everyday the situation gets worse, Charlie doesn't like his high school as kids are mean to him and his old car, meanwhile the younger ones are angry as Tom is always late to pick them up and never has any time for them anymore (the new coaching job requires a lot of public appearances and Tom cant get away from all of it) No babysitter is willing to work with a family as large as the Bakers, so Tom brings the Evanston football players to practice in the living room for Saturday night's football game, as the children do their chores. However, the younger children escape and crash Dylan's birthday party, which they had been forbidden to attend (as Tom had grounded them for fighting in school (Mark was being bullied and the kids stood up for him)). Mark gifts Dylan a live snake, who escapes and creates panic at the party. Tom takes the football team to bring back his kids. But the bouncing castle ends up blowing up throwing Tom on top of Sylan and injuring one football player. Shake is very angry with TOm. When a frustrated and homesick Charlie is kicked off the football team, he accuses Tom of moving for his own reasons and not for the family. Charlie has decided to go back to Midland. Tom discovers that Hank sneaked into the house and slept over with Nora (Nora was there to help Tom at his request) against the family's rules, and Hank upsets Nora by saying he does not want children and expects her to feel the same. Kate gets a call from the children about the chaos, and cancels her book tour. Her publisher decides to create an additional promotion by having Oprah Winfrey film the Bakers in their home. Kate wants Tom to create family feeling in the house, that she has described in the book.Despite Kate's coaching, the Bakers cannot recreate the loving, strongly bonded family she described in her book. When Mark's frog, Beans, unexpectedly dies, Sarah coldly tells him that nobody cares, causing a heated fight to erupt and Oprah's producers to cancel the filming. Mark runs away from home, and when Hank refuses to help search for him, Nora finally realizes Hank's true, selfish nature. She breaks up with him and joins the search, reminding Tom how she used to run away from home to Chicago, her favorite place in the world. Tom has a hunch that Mark is heading for their old home, and finds him on a train to Midland. Reunited, the Bakers begin to address their issues with each other, and hold a little funeral for Beans. Tom resigns to spend more time with his family, and the Bakers celebrate Christmas together as the chandelier in their living room breaks. Kate's book becomes a bestseller. Tom gets 12 job offers and picks one close to home.