| 13273 | Armagh County Museum | 1953/2 | 1900 | Water-colour, monochrome, 'Ballinahone, Armagh, 1900... | |
| 13274 | Armagh County Museum | 1975/35 | 1900 | Copy will of Miss Ann Bakewell, Eddowes and Sons, De... | |
| 12776 | Armagh Diocesan Archive (RC) | | 1898
1901 | There is a detailed calendar of Letters of Most Rev.... | Cardinal Logue Archive |
| 16409 | Armagh Diocesan Archive (RC) | | 1889
1900
1919
1926 | Material relating to the Religious, includes:Folder ... | Cardinal O'Donnell Archive |
| 16444 | Armagh Diocesan Archive (RC) | | 1900 | There is a detailed calendar of Letters of His Emine... | Cardinal Logue Archive |
| 16445 | Armagh Diocesan Archive (RC) | | 1901 | There is a detailed calendar of Letters of His Emine... | Cardinal Logue Archive |
| 16446 | Armagh Diocesan Archive (RC) | | 1901 | There is a detailed calendar of Letters of His Emine... | Cardinal Logue Archive |
| 19152 | Armagh Robinson Library | Volume 1900-1909 | 1900 | An extract from the Church of Ireland Gazette on the... | Dean Rennison Papers |
| 16215 | Birr Castle Archives | A-W | 1900 | M/30: Letters and papers regarding the marriage sett... | The Rosse Papers |
| 20700 | Clare County Archives | | 1901 | Kilkee Town Commissioners, Board Minute Books, Augus... | Kilkee Town Commissioners |
| 20764 | Cork Public Museum | AQNOL1970:44/ | 1899
1901 | 2 Routine matters, containing correspondence, notice... | |
| 528 | County Museum, Dundalk | Lot 208 | 1900 | Woman standing outside a hotel, Clanbrassil Street, ... | Photographs |
| 19048 | Cultural Heritage Services Library, Armagh | | 1901 | Copy of the census returns for County Armagh: 1901 (... | |
| 7574 | Down County Museum | DB496 | 1900 | Printed programme of a Union Jack Concert held in ai... | |
| 18516 | Dublin Diocesan Archives (RC) | AB6 (File 371/1-8) | 1900 | A number of letters from a nun in High Park Convent ... | Walsh Papers |
| 18517 | Dublin Diocesan Archives (RC) | AB6 (File 371/1-8) | 1900 | Letter from a Sister of Charity in Foxford, 11 May, ... | Walsh Papers |
| 18518 | Dublin Diocesan Archives (RC) | AB6 (File 371/1-8) | c.1900 | Typed list regarding St Patrick's, Kilkenny naming t... | Walsh Papers |
| 18520 | Dublin Diocesan Archives (RC) | AB6 (File 371/1-8) | 1900 | Letter from the Presentation Convent in Rathmore, Co... | Walsh Papers |
| 6235 | Enniskillen Library | | 1901 | Microfilm copy of the census of population for Count... | |
| 23156 | Fermanagh County Museum, Enniskillen Castle | FCM-1980-110 | 1900 | A collection of photographs by Annie King in an albu... | Annie King Papers |
| 23153 | Fermanagh County Museum, Enniskillen Castle | FCM-1995-121 | 1901 | Typed memorandum regarding Inishmacsaint lace from t... | Eleanor Hassard Papers |
| 22137 | Irish Jesuit Archives | J27/ | 1883
1887
1901 | 47 December 1883 -5 January 1901. A file of letters... | Papers of Fr Matthew Russell, SJ (1834 - 1912) |
| 21773 | Kerry Diocesan Archives (RC) | C12/23-29 | 1900 | J.G. Eager, Milltown, 1900, Fr Carmody, abuses in pa... | John Coffey, 1889-1904 |
| 21878 | Kerry Local Studies and Archives Department | RDC/100/AF/ | 1900-1901 | 1. Financial Minute Book August 1909 - December 1911... | Kenmare Rural District Council |
| 13272 | Kilmainham Gaol Museum | 17PC-1A44-12 | 1900 | Photo of Countess Markievicz, 1900. | Easter Week |
| 13468 | Kilmainham Gaol Museum | 10LG-1C35-4 | 1900
1921 | Marriage certificate of Casimir Markievicz and Const... | Home Rule |
| 21152 | King's Hospital School | 232-236A | 1900 | 226H Mercer's Rental, 1900. | King's Hospital Records |
| 22300 | Leitrim Local Studies Department | | 1900-1901 | Minute Book:May 1900 - June 1901 | Ballinamore Rural District Council |
| 22369 | Leitrim Local Studies Department | | 1904-1910
1900-1901 | Irish National Foresters' Minute Book, Ballinamo... | Miscellaneous Records, Leitrim |
| 13278 | Limerick Museum | AQNO (0000.4411) | 1901 | Photograph. Glass slide. Group of people, posed. Tit... | |
| 5003 | Maynooth University and St Patrick's College, Maynooth | | 1900 | Letter from Una Farrelly to Eoin MacNeill, 1900. | |
| 14534 | Mayo Local History Department | | 1900 | Minute Book, June 1900-September 1900. | Castlebar Poor Law Union |
| 20134 | Meath Local Studies and Family History Department | Box F/ | 1900 | 15 Bundle of receipts regarding Mountainstown, 1900'... | Mountainstown Documents |
| 20143 | Meath Local Studies and Family History Department | Box C/ | 1900 | 1 Fifty-eight letters (early 1900's) from A.J. Pollo... | Mountainstown Documents |
| 20298 | Meath Local Studies and Family History Department | Box A/ | 1901 | 3 Farm expenditure, Pollocks, 1901. | Mountainstown Documents |
| 11919 | Mount Melleray Abbey, Waterford | | 1901 | See for example: Number 8, Papers of Father Maurus O... | |
| 3929 | National Archives of Ireland | RHK 6/3 | c.1900 | Benevolent Funds: Dublin Garrison Needlework Associa... | Royal Hospital Kilmainham |
| 3937 | National Archives of Ireland | s21340 | 1900 | Lucy Clark, application for post of female detective... | Crime Branch Special Records |
| 3938 | National Archives of Ireland | s2344 | 1900 | Visit of Countess Cadogan to Limerick, 13 December 1... | Crime Branch Special Records |
| 3939 | National Archives of Ireland | s25230 | 1901 | Cipher telegram from Home Office, Crime Department S... | Crime Branch Special Records |
| 3940 | National Archives of Ireland | s24060 | 1900
1901 | 'Daughters of Erin' [Inghinidhe na h-É... | Crime Branch Special Records |
| 4086 | National Archives of Ireland | DUB55/F/B | 1901 | Miscellaneous Deeds etc., relating to the Hospital. ... | Records of the Coombe Hospital |
| 8844 | National Archives of Ireland | IB/1/16 | 1900 | Wills and other Testamentary Records: District Regis... | |
| 8846 | National Archives of Ireland | IB/2/37 | 1901 | Wills and other Testamentary Records: District Regis... | |
| 11493 | National Archives of Ireland | 1189/14/8 | 1900-1901 | Letters to John Woulfe Flanagan, 2 March 1900 -19 Ma... | Woulfe Flanagan |
| 13277 | National Archives of Ireland | PEN1901/77 | 1901 | Jane Irwin, aged 24, born County Leitrim, servant, s... | General Prisons Board Penal Files, 1883-1925 |
| 14101 | National Archives of Ireland | 1190/4 | 1900 | Two letters from Kitty, 1900 and no date. | Sweetman Correspondence |
| 14102 | National Archives of Ireland | 1190/4 | 1901 | Two letters from her brother Joseph, 1901 and no dat... | Sweetman Correspondence |
| 15471 | National Archives of Ireland | 999/71/1 | 1901 | Papers of the Kehoe, Keogh and Keough family, Clough... | Small Private Accessions |
| 15479 | National Archives of Ireland | 999/74 | 1901 | Original probate and copy will of Margaret Topham, 1... | Small Private Accessions |
| 15549 | National Archives of Ireland | 999/165 | 1901 | Copy of probate of the will of Sarah Crowley, 25 Cha... | Small Private Accessions |
| 15589 | National Archives of Ireland | 999/197/2 | 1900 | High Court of Justice Chancery Co. Cavan Trustees of... | Small Private Accessions |
| 15599 | National Archives of Ireland | 999/211/4 | 1901 | Letters of administration intestate of the estate of... | Small Private Accessions |
| 139 | National Library of Ireland | Ms18463 | 1900 | Account by Maura O'Neill Mackey of preparation by Co... | |
| 2315 | National Library of Ireland | Ms13267 | 1901
1911
1916
1920-1929
1930-1939 | Correspondence of theatre critic and enthusiast Jose... | Joseph Holloway Papers |
| 2417 | National Library of Ireland | Ms421 | 1901 | Diary and correspondence relating to Alice Stopford ... | |
| 2444 | National Library of Ireland | Ms9263 | c1901 | Includes a notebook of pious thoughts collected by S... | |
| 2500 | National Library of Ireland | Mss10443-10448 | 1900 | Essays by Alice Stopford Green on various Irish topi... | Alice Stopford Green Papers |
| 2416 | National Library of Ireland | Ms10465(1-7) | 1901 | A diary, letters, photographs and press-clippings re... | Alice Stopford Green Papers |
| 3498 | National Library of Ireland | Ms10957 | c1900 | A calendar of anniversaries of Irish interest compil... | |
| 3742 | National Library of Ireland | Ms 13482 | 1900-1901 | Letters to T P Gill, including letters from, among o... | T.P. Gill Papers |
| 8976 | National Library of Ireland | Ms13526 | 1886
1889
1900 | Lists of: Philadelphia subscribers to the Irish Parl... | T.P. Gill Papers |
| 9029 | National Library of Ireland | Ms13770 | 1901 | Four letters of Major John McBride to his mother whi... | |
| 9255 | National Library of Ireland | Ms15718 | 1901 | Five autographed being the correspondence of Miss C ... | |
| 9373 | National Library of Ireland | Ms23998 | c1900 | Maps and lists of tenants of the estates of the Marq... | Ormonde Papers |
| 9771 | National Library of Ireland | Ms18461 | 1900 | Typescript copy of an incomplete letter to Dr Seamus... | |
| 10080 | National Library of Ireland | Ms16168 | c1900 | Newspaper cuttings referring to Lord Edward Fitzgera... | Lord Walter Fitzgearld Papers |
| 10655 | National Library of Ireland | Mss16695-16696 | c1900 | Draft autobiography in manuscript form of J F X O'Br... | |
| 10973 | National Library of Ireland | Ms22930 | c1900 | Photocopy of a letter from J M Synge to his mother, ... | |
| 11567 | National Photographic Archive | LawrenceR/2215 | c1900 | Ladies bathing place, Portrush Antrim, c1900, includ... | Lawrence |
| 4828 | Newtown School, Waterford | A1/2 | 1900 | Appeals, 1900. | |
| 4830 | Newtown School, Waterford | A/4 | 1900 | Clothing Lists, 1900. | |
| 5406 | Newtown School, Waterford | A1/12 | 1900 | Parents, Letters to, 1900: Newtown School, Waterford | |
| 5407 | Newtown School, Waterford | A1/13 | 1900 | Prospectus, 1900: Newtown School, Waterford | |
| 5511 | Newtown School, Waterford | | 1900 | Parents, Letters to, 1900: Newtown School, Waterford | |
| 5512 | Newtown School, Waterford | 94/507 | 1900 | Prospectus, 1900: Newtown School, Waterford | |
| 21409 | Our Lady's Hospital, Cork | | 1900 | Minutes of the Proceedings of the Committee of Manag... | |
| 21410 | Our Lady's Hospital, Cork | | 1900 | Newspapercuttings Book, c.1900. | |
| 16566 | Presentation Sisters Congregational Archives | DON1/98 | 1901 | Letters of Canon Sheehan to Mother Ita O'Connell... | Presentation Sisters South West Province - St Joseph's Convent, Doneraile |
| 16685 | Presentation Sisters Congregational Archives | | 1900 | Account of the centenary celebrations in September 1... | Presentation Convent, Kilkenny |
| 6605 | Public Record Office of Northern Ireland | D/1717/2 | c1901 | Manuscript notebook with genealogical notes on the O... | |
| 6368 | Public Record Office of Northern Ireland | T/1769 | 1865-1866
1901 | T/1769/3 Copy of the emigrant diary of Elizabeth An... | |
| 6511 | Public Record Office of Northern Ireland | D/1333/ | 1900
1902 | D/1333/152 Separation agreement, James and Annie Qua... | |
| 6515 | Public Record Office of Northern Ireland | D/1364/ | 1856
1900 | D/1364/J/21 Letters from William Young, Fenaghy, Cou... | Young Papers |
| 6536 | Public Record Office of Northern Ireland | D/1493/1 | c.1900 | Bundle of c.50 designs and transfers for embroidery,... | |
| 7131 | Public Record Office of Northern Ireland | D/2884 | c1900 | Photograph of Queen Victoria in a horse drawn carria... | |
| 7400 | Public Record Office of Northern Ireland | D/3931 | c1900 | Volume of prints and photographs by R Welsh of York ... | |
| 8176 | Public Record Office of Northern Ireland | T/1989/1 | c1900 | Genealogical memorandum concerning the Harris family... | |
| 6540 | Public Record Office of Northern Ireland | D/1501/1-6 | c.1900 | Photographs of musical comedy artists, including Mrs... | |
| 6574 | Public Record Office of Northern Ireland | D/1639/1 | c.1900 | Genealogical memoirs of the Archdale family of Castl... | Archdale Papers |
| 6701 | Public Record Office of Northern Ireland | D/1936 | c.1900, c.1930 | Typescript of Gillespie family records, compiled c.1... | |
| 6783 | Public Record Office of Northern Ireland | D/2231 | c.1900 | This collection includes 6 boxes of Butler family pa... | |
| 8186 | Public Record Office of Northern Ireland | T/2017/1 | c1900 | Photograph of the employees of Broadway Damask Compa... | |
| 7886 | Public Record Office of Northern Ireland | T/1129 | c1900 | A copy of a print of Queen Elizabeth I, no date. A ... | |
| 8045 | Public Record Office of Northern Ireland | T/1591 | c.1900 | Copy of a manuscript draft of a speech attacking ... | |
| 8319 | Public Record Office of Northern Ireland | T/2411/1 | c.1900 | Packet of prints of photographs by Welsh of County D... | |
| 1214 | Religious Society of Friends in Ireland Historical Library | P145 | 1900 | Mounted unframed photograph, c1900. Including Susan ... | Photographic Collections |
| 5204 | RTÉ Stills Library | 0259/052 | 1900 | Women dressed in traditional Irish clothing in c.190... | Illustration Library |
| 7592 | St Malachy's College, Belfast | E2 | 1898
1900 | One folder which includes:A handwritten diary of Can... | |
| 10121 | Trinity College Dublin, Manuscripts and Archives Department | TCDMs102471/1/1-17 | 1846
1853
1858
1900 | Correspondence of female members of the Wynne family... | Wynne Family Papers |
| 10297 | Trinity College Dublin, Manuscripts and Archives Department | TCDMs8968 | 1900-1901 | English Language Lecture Notebook of Catherine B Sen... | |
| 11933 | Trinity College Dublin, Manuscripts and Archives Department | TCDMs10221 | 1901 | Diary of Nancy Campbell, 1901. | Joseph Campbell Papers |
| 1620 | UCD Special Collections | OL Ms14 | 1900 | A collection of songs and riddles in Irish compiled ... | O'Lochlainn Collection |
| 1622 | UCD Special Collections | Box 5 | 1900 | Notebooks of Henry Morris: Gaelic 1900 Envelope 3 10... | Henry Morris Correspondence |
| 18405 | University of Galway Archives | LE22 | 1900 | A photocopy of the printed genealogy of the family o... | Genealogy of Martin Ballinahinch Castle |