U.S. Humanitarian Programs Search Step by Step Instructions on Filling Out Form N-400 U.S. Naturalization Process Explained From Green Card to U.S. Citizenship Replace Lost Naturalization/Citizenship Certificate U.S. Naturalization Oath Ceremony Explained What Are the Eligibility Requirements for U.S. Citizenship? U.S. Citizenship Test and Interview Proof of Citizenship for U.S. Citizens- Documents Used Form N-400 Naturalization Timeline How much is the N-400 Application Fee?