Containing over 4.3 million records, the Ireland 1901 Census is one of only two surviving Irish censuses held by the National Archives of Ireland. A new search facility for the Ireland 1901 Census is now available only on Findmypast, enabling searching by more than one household member, birth year and variants on the spelling of first and last names for the very first time. Search results link through to the free images held on The National Archives of Ireland website, making it easier to find your Irish ancestors than ever before.

Ireland is unusual among English-speaking census-taking countries in that original household manuscript returns survive. These are the forms filled out and signed by the head of each household on census night. Most other countries only have Enumerators' books, where family details were transcribed by the person charged with collecting the census information. The basic topographical divisions for the census are: County; District Electoral Division; Townland or Street. The returns are arranged in clusters by townland or street within district electoral division within county.

Each record contains a transcript and image of the original document. Census forms recorded the name, age, sex, relationship to head of the household, religion, occupation, marital status, and county or country of birth of all household members. The census also records an individual's ability to read or write and ability to speak the Irish language, and whether deaf, dumb, blind, idiot, imbecile or lunatic.