The origins of Once Upon a Time In America lie in an autobiographical book "The Hoods" written by Harry Grey (real surname Goldberg) and published in America in 1952.  Leone read this book in the early 1960's but acquiring the rights proved to be difficult and protracted.  The rights had been sold to Dan Curtis who wanted to produce a version of The Hoods himself.  In 1976 Leone turned to Albert Grimaldi who persuaded Curtis to give up the rights in exchange for Grimaldi financing a replacement movie - "Burnt Offerings" with Oliver Reed and Bette Davis.  Grimaldi was convinced that the film script had to be written by a well known American and Mickey Knox introduced one of his close friends, Norman Mailer, to Leone.  Mailer barricaded himself in a Rome hotel room with several bottles of whiskey, a typewriter and some boxes of cuban cigars for a period of 3 weeks. Mailer then had a meeting with Grey and finished the script but Leone did not find it acceptable.

Leone then turned to two of the most respected writers in the Italian film business: Franco 'Kim' Arcalli and Enrico Medoli.  Medioli had worked on many Visconti films including Rocco and his brothers, The Leopard, The Damned and Ludwig.  After several months' work, Leone, Arcalli and Medioli completed a draft script of some 300 pages. While Arcalli worked on finding pratical solutions to the draft's time games, Leone took Medioli to New York to inspect locations and introduce him to Harry Grey.  Harry Grey was more forthcoming and talked of his association with Frank - thought to be Frank Costello.

When Leone returned to Rome, he called in the writing duo of Leonardo Benvenuti and Piero De Bernardi - active since the mid 50s and known as the most prolific writing team in Italy. He also seconded a young film crtic called Franco Ferrini who had freelanced on various specialized magazines and in 1971 had been commissioned to devote a complete issue of Bianco e Nero to Leone and the Antiwestern.  Arcalli, a co-writer and editor for Bertolucci, died suddenly in 1978, four years before shooting began.  Parts of the script still sounded like a translation and Luca Morsello suggested that Leone contact Stuart Kaminsky who was Jewish, had written mysteries set in 1940's Hollywood, and was an admirer of Leone's work.

In 1984 Leone unambiguously cited Kaminky and Benvenuti as the principal contributors who concluded the screenplay.  Due to contractual complications arising from the Ladd Company's re-editing of the finished film, Kaminsky is credited solely with additional dialogue, but he in fact crafted all of the film's dialogue.  According to Kaminsky's account, Benvenuti was primarily responsible for devising the physical visual action of scenes while Medioli's principal contribution to the collective scripting process at this advanced stage was to insure that we remembered the epic nature of the film to be shot.  Kaminsky who also spent several weeks working specifically with De Niro regards his major creative contribution as turning the characters (i.e. Noodles & Max) into distinct individuals representing opposite ends of a spectrum.

Writers:

Harry Grey (novel "The Hoods")

Leonardo Benvenuti
Piero De Bernardi
Enrico Medioli
Franco Arcalli
Franco Ferrini
Sergio Leone

Stuart Kaminsky (additional dialogue)

Ernesto Gastaldi uncredited

The screenplay may be downloaded as a text file or pdf

http://msb247.awardspace.com/docs/once.rtf (rtf file)

http://www.dailyscript.com/scripts/Once_Upon_A_Time_In_America.pdf (pdf version)

The actual dialog from the movie and some scene details: