National Archives of Ireland, Census Records for Ireland 1901 and 1911

The household returns and ancillary records have been digitised and are available online for free. This fully searchable site offers a basic name, age and place search. Other search options available include religion, occupation, relationship to head of family, literacy status, county or country of origin, Irish language proficiency, specified illnesses, and child survival information. There is also a browse by county option available.