Carroll Baker
— Sylvia: West (Karoki, Kay, Carlyle)
George Maharis
— Alan Macklin
Joanne Dru
— Jane (Bronson) Phillips
Peter Lawford
— Frederic Summers
Viveca Lindfors
— Irma Olanski
Edmond O'Brien
— Oscar Stewart
Aldo Ray
— Jonas Karoki
Ann Sothern
— Mrs. Argona / Grace Argona
Lloyd Bochner
— Bruce Stamford III
Paul Gilbert
— Lola Diamond
Jay Novello
— Father Gonzales
Nancy Kovack
— Big Shirley
Gene Lyons
— Gavin Cullen
Anthony Caruso
— Wilbur (aka "Muscles")
Alan Carney
— Gus
Shirley O'Hara
— Mrs. Karoki
Ricky Allen
— Herbert, the Boy in the Library (uncredited)
Val Avery
— Pudgey Smith (uncredited)
Majel Barrett
— Anne (uncredited)
Jean Del Val
— Maitre'd (uncredited)
Connie Gilchrist
— Molly Banter (uncredited)
Gavin Gordon
— Butler (uncredited)
Clive Halliday
— Calligraphy Professor (uncredited)
John Harmon
— Sid (uncredited)
Stacy Harris
— Mr. Leland (uncredited)
Kathleen Mulqueen
— Assistant Principal (uncredited)
Manuel Padilla Jr.
— Pancho Guzman (uncredited)
Robert Random
— (uncredited)
Gene Roth
— Professor Eglebert (uncredited)
Geraldine Wall
— Clerk at Private Hospital (uncredited)