In a number of very popular short stories, journalist and author Damon Runyon created a cartoon-like fantasy of New York peopled by colorful and basically good-hearted gamblers, thieves and other denizens of the Broadway-Times Square area; characters with names like Liver Lips Louie, Angie the Ox, Harry the Horse, Benny Southstreet, and Society Max. The hilarious situations he created for them, as well as a unique brand of Manhattan street talk, almost entirely eschewing contractions, made the coinage "Runyonesque" a widely common term by the time Jo Swerling and Abe Burrows adapted his story, "The Idyll of Miss Sarah Brown," into a hit Broadway musical in 1950 (with songs by Frank Loesser). The title of the play came from a 1931 collection of Runyon's stories.

Producer Samuel Goldwyn was determined to turn the play into a big budget smash film, and paid $1,000,000 against ten percent of the profits for the rights, one of the highest figures ever paid for a stage property. Goldwyn was so convinced he could make an epic hit musical out of the picture, he spent $5.5 million to produce it.

Accustomed to working with some of the major directors in the business (among them William Wyler, Howard Hawks, and King Vidor), Goldwyn hired writer-director Joseph L. Mankiewicz, the Oscar®-winning creator of A Letter to Three Wives (1949) and All About Eve (1950). Mankiewicz took on the task of adapting the script, which he felt was rather thin. He decided to preserve the charm and humor of the original and remain faithful to Runyon's language and characters while fleshing out the characters, particularly the four leads. So he wrote a script that could work as a straight comedy. With the addition of the songs, Mankiewicz's adaptation would have run close to four hours (the completed film came in at 2 1/2 hours). But Goldwyn didn't balk. Famous for his malapropisms and mangled language, the producer told the director, "You write with great warmth and charmth."

Goldwyn ruled that he needed major box office stars to carry his blockbuster. The role of smooth gambler Sky Masterson was at first intended for Gene Kelly, whose musical talents and screen image were well suited to the role. But Kelly's studio, MGM, wouldn't lend him out for the picture (ironically, MGM eventually made a deal for the film's distribution rights). Several other big names (Burt Lancaster, Kirk Douglas, Robert Mitchum (and some lesser ones (singer Tony Martin) were bandied about. Bing Crosby fought hard to be cast, and Clark Gable expressed interest. At one point, Goldwyn hit on the idea of having Dean Martin and Jerry Lewis (who had starred in the 1954 Runyon adaptation Money from Home) play Sky and crap game promoter Nathan Detroit, but Mankiewicz put a stop to that notion. Finally they chose Marlon Brando, who had made a name for himself as a new type of actor and screen anti- hero in such films as A Streetcar Named Desire (1951), The Wild One (1954), and On the Waterfront (1954), for which he won his first Academy Award.

Seeking to expand his image and range beyond the brooding bad-boy roles for which he was known, Brando was intrigued by the idea of making a musical. But he was reluctant because of his lack of experience. Mankiewicz, who had recently directed the young star in Julius Caesar (1953), wired him: "You have never done a musical, neither have I. We never did Shakespeare either. I am confident this would be exciting, gratifying, and rewarding experience for both of us." Brando was won over, receiving $200,000 for 14 weeks work and top billing.

Frank Sinatra was determined to win a key role in the film, too. There was no initial conflict with the Brando decision, however, because after reading the script, Sinatra wanted the more comic role of Nathan Detroit. Although Sinatra was a peerless musical talent whose stock in Hollywood had risen again after his Supporting Actor Oscar® for From Here to Eternity (1953), Mankiewicz thought he was all wrong for the part and still hoped to get Sam Levene, who created the role on stage. But Goldwyn liked the idea - and the box office potential - of pairing Sinatra with Brando.

For the part of missionary Sarah Brown, Goldwyn wanted Grace Kelly, an Oscar® winner for The Country Girl (1954). When she turned the part down because of prior commitments, Goldwyn approached Deborah Kerr, who was also unavailable. He hired his third choice, Jean Simmons, who had just appeared in the title role of Desiree (1954) with Brando as Napoleon. Goldwyn turned out to be delighted with this decision, and Simmons claims to have learned she wasn't the first choice when he came up to her after watching the day's rushes and said, "I'm so happy that I couldn't get Grace Kelly."

Goldwyn wanted Betty Grable to play Adelaide, but she was also unavailable. That gave Mankiewicz his wish to cast the play's original, Vivian Blaine, passing over a request for the role by Marilyn Monroe via phone. Also brought in from the stage production were supporting players Stubby Kaye (who Goldwyn referred to as "Stubby Toe"), B.S. Pulley, and Johnny Silver, and choreographer Michael Kidd.

The casting of the movie required some changes in the script, particularly the musical numbers. Mankiewicz played up the romance between Sky and Sarah, and their scenes have almost none of the Runyonesque lingo and cadence. He also dropped the original plot point of having Sky join the mission as a salvation worker at the end. Due to Brando╒s limitations as a singer, two of the play╒s most beautiful numbers were dropped ╨ "My Time of Day," Sky's paean to the Broadway nightlife, and his romantic song to Sarah, "I've Never Been in Love Before." (The melodies of both songs, however, are heard in the background of some scenes.) "I've Never Been in Love Before" was replaced by a new song written for the film by Frank Loesser, "A Woman in Love." On stage, Nathan Detroit had only one major musical number, "Sue Me." To take advantage of Sinatra's talents, Loesser added the liltingly romantic "Adelaide." In the case of Vivian Blaine, who was recreating her Broadway role, her signature number, the country parody "A Bushel and a Peck" (which subsequently became a popular radio hit), was dropped and replaced with a new one, "Pet Me, Papa."