The Old Age Pension search summaries for Northern Ireland, bound in books and held in Belfast, cover the counties of Antrim, Armagh, Down, Fermanagh, Londonderry, and Tyrone. In some cases a fairly complete family census record was written in the summary book, and it is from these summary books that this present series of census abstracts derives. (Most of the Old Age Pension records contain only brief notes recording whether or not a census record was found for the applicant and whether the age given by the applicant matched the census information.) Only a fraction of the population is covered by these summary book abstracts, wherein altogether a total of 23,000 persons are identified. Generally speaking, the abstracts contain the following information: (1) the name of the head of household; (2) often his marriage date; (3) the wife's name (and sometimes her maiden name); (4) the place of residence for that year; (5) names of children and their ages; (6) names of other members of the family living in the household; and (7) persons having died in the ten years previous to the census. Entries are in alphabetical order and are cross-indexed for relatives, lodgers, visitors, and servants. There are also cross-indexes for married and maiden names of daughters and wives. In addition to the census abstracts taken from the summary books found in the Old Age Pension records, this work also contains census fragments and miscellaneous census data found in both the Public Record Office of Northern Ireland (Belfast) and the National Archives in Dublin. So all is not lost after all, and thanks to the diligence of Mrs. Masterson, we have an unexpectedly powerful tool for filling in gaps in mid-19th-century Irish census records!