Catholic Church in Ireland
In the 2016 Irish census 78.3% of the population identified as Catholic in Ireland; numbering approximately 3.7 million people. Unlike Catholics in the United States, Ireland has seen a significant decline from the 84.2% who identified as Catholic in the 2011 census.
Northern Ireland
Several studies and surveys carried out between 1971 and 2006 have indicated that, in general, most Protestants in Northern Ireland see themselves primarily as British, whereas a majority of Roman Catholics regard themselves primarily as Irish. This does not, however, account for the complex identities within Northern Ireland, given that many of the population regard themselves as "Ulster" or "Northern Irish", either as a primary or secondary identity. Overall, the Catholic population is somewhat more ethnically diverse than the more homogeneous Protestant population. 83.1% of Protestants identified as "British" or with a British ethnic group (English, Scottish, or Welsh) in the 2011 Census, whereas only 3.9% identified as "Irish". Meanwhile, 13.7% of Catholics identified as "British" or with a British ethnic group. A further 4.4% identified as "all other", which are largely immigrants, for example from Poland.