In the early 1960s, the National Library in Dublin undertook a project to index the surnames occurring in Griffith's Valuation and the Tithe Books and produced the county-by county series known as the Index of Surnames or Householders Index. This records the occurrence of households of a particular surname in each of the civil parishes of a county, giving the exact number of households in the case of Griffith's, as well as providing a summary of the total numbers in each barony of the county.

Since it is not a true index, providing only an indication of the presence or absence of a surname in the Tithe Books, and the numbers of the surname in Griffith's, its usefulness is limited. For names that are relatively uncommon, it can be invaluable, but is of little assistance for a county in which a particular surname is plentiful.

It is most frequently used as a means of narrowing the number of parish records to be searched in a case where only the county of origin of an ancestor is known. The county volumes include outline maps of the civil parishes covered and a guide to the corresponding Catholic parishes.

Full sets of the Index of Surnames can be found at The National Library, The National Archives, The Public Record Office of Northern Ireland and the Genealogical Office.

A similar index, but for Griffith's only, is searchable online at www.ireland.com/ancestor.

In recent years, a number of full-name indexes to Griffith's have been produced on microfiche by All-Ireland Heritage and Andrew Morris, both in the US. These list alphabetically all the householders in the Valuation and show the townland and civil parish in which the entry is recorded.

The All-Ireland Heritage microfiche set covers all of Ireland, while the Morris transcripts cover Counties Mayo and Wicklow. As aids to locating individual families in these counties at the time of the Valuation, they are invaluable. However, they are not widely available as yet. The National Archives has copies of the indexes for Cork city and county, Dublin city, and County Fermanagh, while the National Library has copies of most of the indexes.

These indexes have now been replaced by the CD-ROM index to the entire Valuation published in 1997 in the Family Tree Maker 'Family Archives' series by Broderbund Software, in association with Heritage World of Dungannon and the Genealogical Publishing Company. The CD has the potential to be one of the most significant tools ever created for Irish genealogy, particularly for those who do not know the area of origin in Ireland. It needs to be used with some caution, however - McCarthy, for instance, may be included as 'Mc Carthy', 'Mcarthy', 'M'Carthy' etc. and there are significant numbers of errors and omissions. Also most of Limerick city appears to be missing.

If your ancestors do not appear where you think they should, check the originals. Despite any flaws, however, it is a very welcome resource. It is available to the public at the National Library.

In the same series, a CD entitled somewhat misleadingly 'International Land Records: Tithe Applotment Books 1823-38' includes a database transcript of the Tithe Books for the six counties of Northern Ireland.