Koster's postwar career was equally successful. He was nominated for an Academy Award for "The Bishop's Wife" (1947). In 1950, he directed his biggest success: the James Stewart comedy "Harvey". He directed Richard Burton's first U.S. film, "My Cousin Rachel", and then in 1953, he was given "The Robe", the first CinemaScope film. He directed more costume dramas, including "Désirée" (1954) with Marlon Brando, "The Virgin Queen" (1955) with Bette Davis, "The Naked Maja" (1958) with Ava Gardner and "The Story of Ruth" (1960) with Elana Eden, then returned to family comedies and musicals, including "Flower Drum Song" for Universal in 1961. His last picture was "The Singing Nun" in 1965. Koster retired to Leisure Village in Camarillo, California, where he painted a series of portraits of the movie stars with whom he worked.