From 1800 to 1922 the UK was the United Kingdom of Great Britain and Ireland. In other words, for almost all of the period of interest to genealogists, the two islands formed part of the same country.

The first implication is that no official records of migration exist, since the Irish in Britain at this period were not technically immigrants. Another result is that British archives contain much original material of Irish interest. Follow the link to find more information on Irish Records in the United Kingdom.

There are strong similarities between the record systems of Britain and Ireland, particularly:

However, some very significant differences need to be taken into account:

There are four categories of Irish records that are relevant to almost everyone doing research on Irish ancestors. These are:

State registration of non-Catholic marriages began in Ireland in 1845. All births, deaths and marriages have been registered in Ireland since 1864. The main points of research access are:

Research in the Belfast Office is limited by space constraints, and pre-booking up to two weeks in advance may be necessary. Research in the Dublin Office is allowed on the indexes only, with the purchase of a photocopy necessary to obtain further information.

Read more about researching in the GRO Dublin.

Full government censuses were taken of the whole island in 1821, 1831, 1841, 1851, 1861, 1871, 1881, 1891, 1901, and 1911. The first four, for 1821, 1831, 1841 and 1851, were largely destroyed in 1922 in the fire at the Public Record Office, Dublin (surviving fragments are detailed in the county source-lists).

Those for 1861, 1871, 1881 and 1891 were completely destroyed earlier, by order of the government, for reasons that deserve more investigation. This means that the earliest surviving comprehensive returns are for 1901 and 1911.

Because of this, the normal rule that census returns should not be available to the public for 100 years has been suspended in the Republic of Ireland. The returns for both 1901 and 1911 can be consulted on microfilm in the Public Record Office of Ireland.

A full microfilm copy of the 1901 census is available at the LDS Family History Library in Salt Lake City and through local Mormon Family History Centres. Indexes, in published or database form, are available for the 1901 returns of some counties.

Copies of the 1901 returns for the six counties now in Northern Ireland are available at the Public Record Office of Northern Ireland. In addition, some of the local heritage centres have computerised transcripts of the 1901 census returns for their areas.

Read more about the 1901 and 1911 census.

Find out more about census substitutes and fragments.

Through the 19th century about 85% of the population of Ireland were Roman Catholic, 5% were members of the Church of Ireland and 10% Dissenters, almost all Presbyterian and mainly, but not exclusively, concentrated in the North.

Before the start of civil registration for all in 1864, the records of these churches are virtually the only direct sources of family information.

For information on the records of any of the religions or denominations listed below follow the appropriate link.

Because of the destruction of 19th-century census returns, surviving land and property records from the period have become significant for genealogical research. Two surveys cover the entire country:

There are also a number of transcripts and finding aids for these. The records of the Valuation Office, originally set up to oversee the Primary Valuation, can also be invaluable and the records of the great landed estates can sometimes provide useful information.

In your search of property records the details provided in the categories below will be invaluable. Follow any of the links below for further information on that specific subject area.

Of records that are only relevant in specific circumstances the most important are:

Irish commercial directories completely exclude servants, small tenant farmers and landless labourers, which were the classes that made up the vast majority of the Irish population up to the 20th century. However, for those areas and classes that they do cover, Irish directories are an excellent source, often supplying information not readily available elsewhere. Follow the link Dublin, Countrywide and Provincial Directories for more detailed information about directories.

Newspapers are a genealogical source that should be approached with caution, especially if time is limited - it is simply too easy to be drawn into the journalistic details of the past. They can, however, provide the kind of information absent from almost all other records.

For more on how newspapers may help your research please follow the link below for details.

Read more about Newspaper Indexes and Locations

Once again, the most disadvantaged - those most likely to migrate, in other words - are least likely to have been in an occupation for which records survive. But if records do exist, they can be extremely useful. Two of the most important sets of occupational records are available in the National Archives, Kew, those of:

With the obvious limitation that wills are only relevant for the minority who owned property, they can be an extremely important source of genealogical information in Ireland as elsewhere. They provide a clear picture of a family at a particular point in time and can often supply enough details of a much larger network of relationships to produce quite a substantial family tree.

Researching testamentary records - the records of wills - can be difficult anywhere but in Ireland the difficulty is greater because almost all of the testamentary holdings of the Public Record Office (now the Public Record Office of Ireland) were destroyed in 1922. Many of the substitutes now used are scattered and fragmented. Many wills of Irish subjects were probated in Britain, so it is worth checking the PRO records, some of which are now online: www.nationalarchives.gov.uk/documentsonline.

Read more about Testamentary authority before 1857 and after 1857.