Baker family •
Steve Martin as Tom Baker, the patriarch of the Baker family •
Bonnie Hunt as Kate Baker, the matriarch of the Baker family who is the narrator of the film •
Piper Perabo as Nora Baker, the eldest Baker child •
Tom Welling as Charlie Baker, the second Baker child •
Hilary Duff as Lorraine Baker, the third Baker child •
Kevin G. Schmidt as Henry Baker, the fourth Baker child •
Alyson Stoner as Sarah Baker, the fifth Baker child •
Jacob Smith as Jake Baker, the sixth Baker child • Forrest Landis as Mark Baker, the seventh Baker child •
Liliana Mumy and
Morgan York as Jessica and Kim Baker, the eighth and ninth Baker children and fraternal twin sisters •
Blake Woodruff as Mike Baker, the tenth Baker child •
Brent and Shane Kinsman as Nigel and Kyle Baker, the youngest Baker children and identical twin brothers
Others •
Paula Marshall as Tina Shenk, the neighbor of the Bakers •
Alan Ruck as Bill Shenk, Tina's husband •
Steven Anthony Lawrence as Dylan Shenk, Tina & Bill's son •
Richard Jenkins as Shake McGuire, Tom's friend and boss •
Vanessa Bell Calloway as Diane Phillips, Kate's publisher •
Tiffany Dupont as Beth, Charlie's girlfriend •
Cody Linley as Quinn •
Dax Shepard as Camera Crew Member •
Amy Hill as Miss Hozzie, Nigel and Kyle's kindergarten teacher •
Ashton Kutcher as Hank, Nora’s boyfriend. •
Shawn Levy as a reporter •
Jared Padalecki as a bully who causes problems for Charlie •
Wayne Knight as Pete, the electrician whose repairs on the Bakers' chandelier in the hallway cause him to fall off of his ladder in two different incidents. •
Regis Philbin as himself •
Kelly Ripa as herself ==Soundtrack==