A. In most cases, Irish surnames are relatively common. Unless you have a really uncommon surname that comes from only one or two counties in Ireland, you need to determine a specific place of origin in Ireland from US records before you go searching in Irish records.

Naturalization papers can be a good source for this information, depending on the time period and locality. Remember, you'll want to examine both the Declaration of Intention and the Petition for Naturalization. These two documents were usually filed years apart and could have been filed in different courts. They may contain significantly different information. Websites including Ancestry.com, Fold3.com and FamilySearch.org have collections of naturalization records or indexes for various places and years; also see our tips for finding ancestors' citizenship papers.

Records generated when the immigrant ancestor died also are good possibilities for finding a place of origin in Ireland: death certificates, cemetery registers, tombstones, church burial records, obituaries, funeral home records, funeral cards. It is also helpful to know the immigrants' parents' names, especially the mother's maiden name. Family Tree University's Irish Research 101 course (also available as an Independent Study course) is designed to help you pinpoint your ancestor's place of birth in Ireland.

Also, you should be tracing not only your grandfather but all other relatives who came over from Ireland, to see whether their records give the county they came from. This includes siblings and other relatives who may have settled in other countries abroad.