Logan Lerman as Charlie

Emma Watson as Sam

Ezra Miller as Patrick

Mae Whitman as Mary Elizabeth

Kate Walsh as Mother

Dylan McDermott as Father

Melanie Lynskey as Aunt Helen

Nina Dobrev as Candace

Johnny Simmons as Brad

Joan Cusack as Dr. Burton

Paul Rudd as Mr. Anderson

Nicholas Braun as Ponytail Derek

Reece Thompson as Craig

Patrick de Ledebur as Senior Bully

Brian Balzerini as Linebacker

Tom Kruszewski as Nose Tackle

Julia Garner as Susan

Tom Savini as Mr. Callahan

Emily Marie Callaway as Mean Freshman Girl

Chelsea Zhang as Shakespeare Girl

Jesse Scheirer as Freshman Boy

Justine Nicole Schaefer as Twin Girl #1

Julie Marie Schaefer as Twin Girl #2

Leo Miles Farmerie as 7-Year-Old Charlie

Isabel Muschweck as 9-Year-Old Candace

Adam Hagenbuch as Bob

Erin Wilhelmi as Alice

Jordan Paley as Rocky MC

Zane Holtz as Chris

Timothy Breslin as Policeman

Mark McClain Wilson as Emergency Room Policeman

Atticus Cain as Emergency Room Doctor

Stacy Chbosky as Young Mom

Dihlon McManne as Priest

Laurie Klatscher as School Principal

Landon Pigg as Peter

Jennifer Enskat as Sam's Mom

William L. Thomas as Patrick's Dad

Morgan Wolk as Candace's Friend

Joe Fishel as Father of Twin Girls (uncredited)