First thing that one would require to become a US citizen is the Green Card. For that they need a sponsor. Once obtained a Green card, then they have to be a green card holder for 5 years ( 3 yrs for conditional residents). Third is maintaining a continuous residence in the US. They also need to be 18 yrs of age. Finally they must be able to speak, write and read normal English and have sufficient knowledge about the history of the US constitution.