Anton Yelchin as Charlie Bartlett

Robert Downey Jr. as Nathan Gardner

Hope Davis as Marilyn Bartlett

Kat Dennings as Susan Gardner

Tyler Hilton as Murphy Bivens

Mark Rendall as Kip Crombwell

Dylan Taylor as Len Arbuckle

Megan Park as Whitney Drummond

Jonathan Malen as Jordan Sunder

Stephen Young as Dr. Stan Weathers

Ishan Davé as Henry Freemont

Dave Brown as Officer Hansen

Eric Fink as Thomas

Noam Jenkins as Dean West

Lauren Collins as Kelly

Annick Obonsawin as Daisy

Sarah Gadon as Priscilla

Drake as A/V Jones

Michael D'Ascenzo as Scott

Dwayne McLean as Bus Driver

Quancetia Hamilton as Mrs. Albertson

Richard Alan Campbell as Dr. Sam Costell

Kim Roberts as Dr. Linda Jenkins

David Fraser as Dr. Jacob Kaufmann

Marvin Karon as Dr. P. Sarossy

Abigail Bernardez as Cheerleader #1

Laura Jeanes as Cheerleader #2

Annamaria Janice McAndrew as Cheerleader #3

Amelia Tenttave as Len's Girlfriend #1

Annabelle Singson as Len's Girlfriend #2

Julia Cohen as Receptionist

Abby Zotz as Kip's Mom

Maddy Wilde as Spiral Beach Band Member

Dorian Wolf as Spiral Beach Band Member

Airick Woodhead as Spiral Beach Band Member

Daniel Woodhead as Spiral Beach Band Member

Jake Epstein as Dustin Lauderbach

Brendan Murray as Dorm Head

Derek McGrath as Superintendent Sedgwick