Due to a variety of unfortunate circumstances, most of Ireland's early census records no longer exist however, 1901 does exist. It is quite an interesting census and offers up some useful information to genealogists.
I know what you are thinking, my ancestors are famine immigrants, what can this census from so many years later do for me? Well let me tell you what it did for me, it introduced me to my third great uncle.
If you have used the National Library of Ireland parish records to find your ancestors' baptism and marriage records, you will know that they had siblings. In my particular case, I located the marriage record of my second great grandfather's brother in 1874. How do I know it is his brother? By this time, the parents listed on the marriage record.
This is one of the most important and exciting discoveries that I have ever made. Why you ask? Because Edmond/Edward had 8 children. One at least was married by the time of the 1911 census and had children. I now know that if I see someone who is a cousin shows up with the last name McCarthy, they may actually be a descendant of Geoffrey Donahue and Johanna Sulivan like I am.
For years I have assumed that I had no relatives who might still be living in Ireland today. I now know that it is at least possible that I have relatives and maybe they still live in the Killarney area. This is exciting stuff after so many years of finding nothing on this line.
What the 1901 census included is head of household, occupation, the age of all the household members, sex, literacy, religion, and relationship to head of the home.
If you haven't looked at the 1901 Census of Ireland, give it a look, you have nothing to lose and a world of information to gain. The records are located on the National Archives of Ireland website.