Zac Efron as Mike O'Donnell

Leslie Mann as Scarlett O'Donnell

Thomas Lennon as Ned Gold

Michelle Trachtenberg as Maggie O'Donnell

Sterling Knight as Alex O'Donnell

Matthew Perry as Mike O'Donnell (Adult)

Tyler Steelman as Ned Gold (Teen)

Allison Miller as Scarlett (Teen)

Adam Gregory as Dom

Hunter Parrish as Stan

Mario Cassem as Samir

Kat Graham as Jamie

Tiya Sircar as Samantha

Melissa Ordway as Lauren

Melora Hardin as Principal Jane Masterson

Brian Doyle-Murray as Janitor

Josie Loren as Nicole

Jim Gaffigan as Coach Murphy

Randy Gordon as Photographer

Collette Wolfe as Wendy

Tommy Dewey as Roger

Linda Miller as Female Janitor

Lorna Scott as Secretary

Kodi Kitchen as Hostess

Ellis Williams as Bailiff

Diana Maria Riva as Judge

Jeff Snyder as Waiter

Antonio Todd as Referee (1989)

Angee Hughes as Waitress

Ed Ackerman as School Cop

Will Schaub as Referee

Loren Lester as Mike's Lawyer

Alexander George as Kid in Hallway

Nicole Sullivan as Naomi

Margaret Cho as Mrs. Dell

Larry Poindexter as Dean

Bubba Lewis as Dorky Kid (Ned's Party)

Chris Valenti as Syracuse Scout (1989)

G. Lane Hillman as Kevin (1989)

Hope Riley as Girl (Wyatt)

Jeanine Jackson as Scarlet's Lawyer

Gregory Sporleder as Ohio Scout

Keith Oney as Guy in Crowd

Leonard Wu as Kid (Office)

Liana Blackburn as Cheerleader (1989)

Lindsay Taylor as Cheerleader (1989)

Danielle E. Hawkins as Cheerleader (1989)

Shelby Rabara as Cheerleader (1989)

Katrina Norman as Cheerleader (1989)

Tiana Brown Gandelman as Cheerleader (1989)

Rhapsody Violetti as Cheerleader (1989)

Taisha Monique Clark as Cheerleader (1989)

Vanessa Lee Chester as Cheerleader

Chanel Malvar as Cheerleader

Tyne Stecklein as Cheerleader

Galen Hooks as Cheerleader

Kiara Ely as Cheerleader

Mihran Kirakosian as Cheerleader

Rachele Brooke Smith as Hammer Dancer

Jesse Heiman as Mascot

Dres Reid as Cheerleader

Christopher Scott as Hammer Dancer

Eric McCoy as Hammer Dancer

Raymond Chacon as Jazz

Megan Galiber as Girl #2

Renée King as ROTC Leader

Jordan Schatz as Mr. Adams

Jaclyn Matfus as Party Girl

Justin C. Todd as Football Player

Keith Oney as Guy in Crowd