Naturalization records document the granting of US citizenship through judicial proceedings, and INS naturalization records duplicate those found in naturalization courts throughout the country. INS also maintains a variety of citizenship records, among them records relating to derivative citizenship, resumed or restored US citizenship, or loss of US citizenship.

Read more about the history of Women and Naturalization

Prior to September 27, 1906, there was no US Naturalization Service, thus the INS has no naturalization records dated before September 1906. To locate pre-1906 naturalization records, or any naturalization records filed with courts, start your research at the National Archives.

Read about the records of one immigrant's naturalization

Naturalization Certificate Files (C-Files)

INS naturalization certificate files, known as C-Files, include a duplicate copy of all naturalization records dated after September 26, 1906. All C-Files contain at least a copy of the Declaration of Intention (184k) to become a US Citizen (to 1952), Petition for Naturalization (279k), and Certificate of Naturalization (223k). Occasional files contain additional documents or correspondence.

C-Files include all US naturalizations from all States and Territories, and from all courts (Federal, State, and local). INS maintains an index to the C-Files, and can retrieve individual records based on name, date of birth, and place of birth. C-Files from 1906 to 1956 have been microfilmed, and are available via Freedom of Information/Privacy Act request to INS Headquarters in Washington, D.C. For naturalization records after 1956, Freedom of Information requests should be sent to the appropriate INS District Office.

An index to naturalizations of soldiers during World War I may be found at the National Archives.