->'''Rita''': ''"I just don't know what to call you: retarded, mentally retarded, mentally handicapped, mentally disabled, intellectually handicapped, intellectually disabled, developmentally disabled..."''
->'''Sam''': ''"You can call me Sam."''
Sam, a mentally handicapped man, meets a woman who takes advantage of him sexually. Nine months later, she drops a baby girl off and vanishes into the night. Though he's not able to understand all the implications of this, Sam does his best to raise the girl, whom he names Lucy, with the help of some friends.
Lucy turns out to be very bright, but after a while she realizes the gulf between her own intelligence and her father's, and she even starts to [[ObfuscatingStupidity act dumb]] - pretending that she can't read, and so on. When he calls her on this, she confesses that she never wants to be smarter than he is. She's six years old at the time.
Shortly thereafter, the school realizes that Lucy is being raised by a mentally handicapped person, and they report it. Lucy gets taken into foster care pending a court trial to figure out if Sam is capable of raising her. Sam seeks out a pro-bono lawyer, who is initially resistive to the idea of representing him, but eventually gets up to bat with everything she has.
Sam ends up moving in just down the street from the foster home. He's not aware that this is a bad thing. Lucy runs away to Sam's house repeatedly, and he keeps bringing her back to the foster home, because he knows she has to obey the law. Eventually even the foster mother comes around, realizing how much Lucy loves her father, and one night she even brings her over to Sam's house.
The court case goes through, and eventually the verdict is: Sam can raise Lucy, assuming he gets help from the various resources he's proven he's capable of seeking out, to ensure that his daughter is not without proper education.
!!''I Am Sam'' contains examples of the following:
* DisabledCharacterDisabledActor: Creator/SeanPenn, of course, is not really developmentally disabled — but many of the actors who play his housemates ''are''.
* InspirationallyDisadvantaged: Averted.
* IWantMyBelovedToBeHappy: Sam for his daughter.
* WhiteAndGreyMorality: Sam is a mentally handicapped man who is just trying to be with his daughter while the government thinks [[StrawmanHasAPoint (and for good reason)]] that he would be unable to raise her properly.
* JukeboxMusical: Sort of, as the soundtrack consists of cover versions of songs by Music/TheBeatles.
* OscarBait: As pointed out in ''Film/TropicThunder'', Sean Penn tried just a little too hard with this one, not to mention the creative staff behind the movie.
* RealisticDictionIsUnrealistic: Averted entirely when it comes to Sam, who tends to repeat himself and mix his words. Interestingly, the more a character comes to like Sam, the more they talk like him.
** That they start talking like him when they come to like him can be explained by the fact that this happens [[RealLife in real life.]] If you spend a lot of time around people that talk a certain way, then you start [[GotMeDoingIt acting and speaking like them.]] People who spend time in foreign countries develop a different accent or dialect, and people who spend time around someone who, say, says a certain word a lot or has a verbal tic will find themselves using the word or verbal tic.
* ShoutOut: When asked what his daughter means to him, Sam makes a heartfelt speech that the judge points out is from ''Film/KramerVsKramer''.
** There is a screenshot of an episode of ''WesternAnimation/JohnnyBravo'' at one point.
* StarMakingRole: For a young Creator/DakotaFanning.
* TimeShiftedActor: The younger version of Lucy is played by Dakota Fanning's younger sister ElleFanning.
* TragicDream: Sam wants to be a good father, but he just isn't capable of raising his daughter alone.