 In 1940, Vallin (billed as Eric Efron) acted on stage with the Hollytown Theater.Vallin started his Hollywood career with an uncredited part in the film "Freshman Year" and played minor roles in feature films at various studios.In 1942 he joined the Pasadena Playhouse, and received his first co-star billing in the film "The Panther's Claw" together with Sidney Blackmer, and showed promise in "Secrets of a Co-Ed" with Otto Kruger.