One can find a lot of examples of the conflict theory throughout this movie. It is a story most of us have heard many times. The boys grow up, make their own gang, fight their enemies, chase their lovers, and eventually wind up in betrayal. But the story is not told from all their points of view. The tale is told through the eyes of David "Noodles" Aaronson (Robert De Niro). Much of the story deals with his friends, Maxamilian (James Woods) and Philip "Cockeye" Stein (William Forsythe), and his childhood love interest, Carol (Tuesday Weld). Betrayal and friendship is the axis on which Leone’s film twists and turns back and forth in time. It is the friendship between Noodles and his long-time associate Max. Companionship is a key element represented in this movie, and it is shown as a binding and unbending human connection which survives all manner of torment and deception. Ultimately Noodles and Max will fall out and each will betray the other in one way or another but their friendship and the kinship on which it was founded remains intact. In the film’s penultimate sequence the two elderly friends come together and discuss, in veiled terms, the bond they once shared and how it now ties them together despite the impossible predicament they are now in.
This movie is also a good example of functional analysis. Leone strategically employs the gangster genre so as to undercut its usual concerns. Gangster fiction has had a tradition of strong-willed likeable criminals whose illegal affairs have held a special attraction for the viewer. The gangsters of Once Upon a Time in America are quite simply losers. When Noodles returns to New York after a self-imposed thirty-five year exile he tells his old friend Moe: ‘You can always tell the winners at the starting gate - the winners and the losers.’ Noodles then assesses himself as a loser and his estimation is absolutely appropriate. With Once Upon A Time in America Leone examines a world that surveys political corruption, institutionalized violence and bloody betrayal. In the end of the movie one can see how common it is for the criminal mind to betray. It is the usual substance of dreams lost, people killed.
Another theory that can be recognized in the movie is Symbolic Interactionism. Fundamentally Once upon a Time in America is the story of Jewish gangster David “Noodles” Aaronson, his childhood in the slums of New York, his brief rise to a place of prominence within the fertile world of prohibition America and his eventual old-age in which he loses everything, including the belief he has had in his life. The narrative plays out in three sections – 1921, 1933 and 1968 – and explores the relationships Noodles cultivates with various people and importantly examines the relationship he destroys with his childhood love Deborah. Noodles seems to believe he has a right to Deborah’s love but almost every action he takes or movement he makes blocks his opportunity to ensure his dream will be realized. As Noodles faces his past, there is not much left for him but a series of lost memories.
In conclusion, the film teaches us that our characters are nothing more than a bunch of common thugs, pretty much the usual conclusion anyone would have after seeing a film about organized crime. This movie is a ddetailed investigation of a world of big-time aspirants with small-time capabilities.