Trying to trace my fathers nationalization papers?

Question:my father was nationalized between the years of 1943 --1946

Best Answer - Chosen by Asker: my father was nationalized between the years of 1943 --1946

In US?
http://www.uscis.gov/vgn-ext-templating/...

The Immigration and Naturalization website, link for genealogy.

You need to know the state where he resided at the time of his naturalization. The records for that state were sent to one of the National Archives regional centers. Only that center can give you copies of the records. The Immigration and Naturalization Service (nka Immigration and Customs Enforcement) does not hold on to those records forever. Once the file closes, it is sent to NARA for safekeeping.

This site will help you in the process: http://www.archives.gov/locations/