James Stewart as Professor Robert Leaf

Fabian as Kenneth 'Kenny' Taylor

Glynis Johns as Vina Leaf

Cindy Carol as Pandora 'Panny' Leaf

Bill Mumy as Erasmus 'Ras' Leaf

John Williams as Peregrine Upjohn

Brigitte Bardot as Brigitte Bardot

Jack Kruschen as Doctor Volker

Charles Robinson as George

Howard Freeman as Dean Sawyer

Jane Wald as Terry, George's Wife

James Brolin as Student at Leaf Rally

Susanne Cramer as Blonde Doll (Upjohn's Girl)

Ed Wynn as The Captain

Paula Lane as Eugenia Clove

Robert Biheller as Orville

Alice Pearce as Office Clerk