The Census in Ireland is carried out by the Central Statistics Office. The census is carried out every five years, with more detailed information collected in years ending in 1 and less in the years ending in 6. The 1976 census was canceled as a cost-saving measure, but a supplementary census was held in 1979 after it became apparent that the 1970s had seen major demographic changes. The census scheduled for 2001 was postponed until 2002 due to the outbreak of foot-and-mouth disease.

The most recent census took place on 23 April 2006. According to the 2006 form, "any person who fails or refuses to provide information or who knowingly provides false information may be subject to a fine of up to 25,000," under the Central Statistics Act 1993. On the CSO website, instructions for non-English speaking residents of Ireland were available. They were mock copies of the census forms, with all headings/questions etc. being translated into a particular language. These were not to be filled out, but were only a guide on how to fill out the English or Irish form. This census also asked two new questions relating to ownership of PCs and Internet connection.

Data from the Census of Ireland, 1901 and 1911 Census of Ireland were made publicly available in 1961, and are published online. Subsequent census records will be made publicly available 100 years after collection. In June 2010, the 1901 census of Ireland became available on the Internet.

Questions relating to the ability to speak the Irish Language are included in the census. The figures obtained have been criticised as inflated by cognitive biases, such as response bias or wishful thinking. The 2006 census included an additional question on frequency of speaking Irish.

There are some calls for a boycott to the 2011 Census as the Irish Central Statistics Office (CSO) has outsourced the printing, hardware, software and related technical support to CACI. CACI employees were accused of human rights abuses, but have not been found guilty. This may be due to the fact that they have been ruled to have "government contractor immunity" by the US courts. CACI say: "We remain proud of our work in Iraq and our other efforts to help in the war against terrorism.". On foot of concerns that this may effect the 2011 Census, the CSO have released a press statement that CACI will advise on software but cannot access any basic census data.

There have also been two campaigns asking people to consider how they answer the question on religion. As with the question relating to the Irish language, the accuracy of the figures for religious membership have been questioned.

The 2011 Irish Census was conducted on 10 April 2011.