| "The fragility of her sex"? : medieval Irishwomen in their European context | | Monograph or Collective Volume | Four Courts | 1996 |
| "The king's friend" : O'Neill, the crown and the earldom of Ulster | Simms, Katharine | Article in Book | Irish Academic Press | 1981 |
| A lost tribe : the Clan Murtagh O'Conors | Simms, Katharine | Article in Journal | | 2001 |
| A miracle of learning : studies in manuscripts and Irish learning. Essays in honour of William O'Sullivan | | Monograph or Collective Volume | Ashgate | 1998 |
| A poem to a 13th-century Irish lady : Cailleach Dé | Simms, Katharine | Article in Book | | 2010 |
| An eaglais agus filí na scol | Simms, Katharine | Article in Book | | 1994 |
| Appreciation of Philomena Connolly | Simms, Katharine | Article in Book | | 2003 |
| Banqueting and the Medieval Gaelic Chiefs | Simms, Katharine | Article in Book | Royal Irish Academy | 2024 |
| Bardic poems of apology and reconciliation | Simms, Katharine | Article in Book | | 2012 |
| Bardic poems of consolation to bereaved Irish ladies | Simms, Katharine | Article in Book | | 2010 |
| Bardic poetry as a historical source | Simms, Katharine | Article in Book | | 1987 |
| Bards and barons : the Anglo-Irish aristocracy and the native culture | Simms, Katharine | Article in Book | | 1989 |
| Changing patterns of regnal succession in later medieval Ireland | Simms, Katharine | Article in Book | | 2008 |
| Charles Lynegar, the ó Luinín family and the study of Seanchas | Simms, Katharine | Article in Book | | 1998 |
| Colony and frontier in medieval Ireland : essays presented to J.F. Lydon | | Monograph or Collective Volume | Hambledon | 1995 |
| Foreign apologues in bardic poetry | Simms, Katharine | Article in Book | | 2013 |
| From kings to warlords : the changing political structure of Gaelic Ireland in the later Middle Ages | Simms, Katharine | Monograph or Collective Volume | Boydell Press | 1987 |
| Frontiers in the Irish church - regional and cultural | Simms, Katharine | Article in Book | | 1995 |
| Gaelic culture and society | Simms, Katharine | Article in Book | | 2018 |
| Gaelic Ireland (c. 600 – c. 1700) : politics, culture and landscapes. Studies for the ‘Irish Chiefs’ Prize | | Monograph or Collective Volume | Wordwell | 2013 |
| Gaelic Ireland (c.600-c.1700) : lordship, saints and learning. Essays for the Irish Chiefs' and Clans' Prize in history | NA | Monograph or Collective Volume | Wordwell | 2021 |
| Gaelic lordships in Ulster in the later middle ages | Simms, Katharine | Thesis | | 1976 |
| Gaelic military history and the later Brehon law commentaries | Simms, Katharine | Article in Book | | 2004 |
| Gaelic Ulster in the Middle Ages : history, culture and society | Simms, Katharine | Monograph or Collective Volume | Four Courts Press | 2020 |
| Gaelic warfare in the middle ages | Simms, Katharine | Article in Book | | 1996 |
| Guesting and feasting in Gaelic Ireland | Simms, Katharine | Article in Journal | | 1979 |
| Heroes humiliated: a theme in Bardic eulogies | Simms, Katharine | Article in Book | | 2016 |
| Images of the galloglass in poems to the MacSweeneys | Simms, Katharine | Article in Book | | 2007 |
| Images of warfare in bardic poetry | Simms, Katharine | Article in Journal | | 1990 |
| Introduction | Meek, Christine E.Simms, Katharine | Article in Book | | 1996 |
| Introduction | McInerney, Luke ; Simms, Katharine | Article in Book | | 2021 |
| Irish language sources | Simms, Katharine | Article in Book | | 1998 |
| Kells | Simms, Anngret,Simms, Katharine | Monograph or Collective Volume | Royal Irish Academy | 1990 |
| Late medieval Donegal | Simms, Katharine | Article in Book | | 1995 |
| Late medieval Tír Eoghain : the kingdom of the great O Néill | Simms, Katharine | Article in Book | | 2000 |
| Literacy and the Irish bards | Simms, Katharine | Article in Book | | 1998 |
| Literary sources for the history of Gaelic Ireland in the post-Norman period | Simms, Katharine | Article in Book | | 1996 |
| Medieval Armagh : the kingdom of Oirthir (Orior) and its rulers the Uí Annluain (O'Hanlons) | Simms, Katharine | Article in Book | | 2001 |
| Medieval Fermanagh | Simms, Katharine | Article in Book | | 2004 |
| Medieval gaelic sources | Simms, Katharine | Monograph or Collective Volume | Four Courts | 2009 |
| Monaghan in the later middle ages | Simms, Katharine | Article in Book | | 2017 |
| Muireadhach Albanach Ó Dálaigh and the classical revolution | Simms, Katharine | Article in Book | | 2006 |
| Native sources for Gaelic settlement : the house poems | Simms, Katharine | Article in Book | | 2001 |
| Niall Garbh II O Donnell, king of Tír Conaill, 1422-39 | Simms, Katharine | Article in Journal | | 1977 |
| Nomadry in medieval Ireland : the origins of the creaght or caoraigheacht | Simms, Katharine | Article in Journal | | 1986 |
| O'Friel's ghost | Simms, Katharine | Article in Book | | 2015 |
| Poems to the medieval O'Donnell chiefs and their historical context | Simms, Katharine | Article in Journal | | 2017 |
| Politics, kinship and culture in Gaelic Ireland, c. 1100–c. 1690. Essays for the Irish Chiefs’ and Clans’ Prize in History | | Monograph or Collective Volume | Wordwell | 2018 |
| Progress in medieval Irish studies | | Monograph or Collective Volume | Department of Old Irish, St. Patrick's College | 1996 |
| Propaganda use of the Táin in the later middle ages | Simms, Katharine | Article in Journal | | 1983 |
| References to landscape and economy in Irish bardic poetry | Simms, Katharine | Article in Book | | 2004 |
| Relations with the Irish | Simms, Katharine | Article in Book | | 1997 |
| Serfs and Citizens: the church tenants of medieval Armagh | Simms, Katharine | Article in Journal | | 2021 |
| The archbishopric of Armagh and the O'Neills, 1347-1471 | Simms, Katharine | Article in Journal | | 1974 |
| The barefoot kings : literary image and reality in later medieval Ireland | Simms, Katharine | Article in Book | | 2011 |
| The barefoot kings : literary image and reality in later medieval Ireland | Simms, Katharine | Article in Book | | 2011 |
| The barefoot kings : literary image and reality in later medieval Ireland | Simms, Katharine | Article in Journal | | 2010 |
| The battle of Dysart O'Dea and the Gaelic resurgence in Thomond | Simms, Katharine | Article in Journal | | 1979 |
| The brehons of later medieval Ireland | Simms, Katharine | Article in Book | | 1990 |
| The concordat between primate John Mey and Henry O'Neill (1455) | Simms, Katharine | Article in Journal | | 1976 |
| The contents of later commentaries on the Brehon law tracts | Simms, Katharine | Article in Journal | | 1998 |
| The dating of two poems on Ulster chieftains | Simms, Katharine | Article in Book | | 2000 |
| The Donegal poems in the Book of Fenagh | Simms, Katharine | Article in Journal | | 2008 |
| The Geraldines and Gaelic culture | Simms, Katharine | Article in Book | | 2016 |
| The legal position of Irish women in the later middle ages | Simms, Katharine | Article in Journal | | 1975 |
| The literary tradition of Ulster to the sixteenth century | Simms, Katharine | Article in Book | | 2018 |
| The MacMahon pedigree : a medieval forgery | Simms, Katharine | Article in Book | | 2004 |
| The medieval kingdom of Lough Erne | Simms, Katharine | Article in Journal | | 1977 |
| The Norman invasion and the Gaelic recovery | Simms, Katharine | Article in Book | | 1989 |
| The O'Hanlons, the O'Neills, and the Anglo-Normans in thirteenth-century Armagh | Simms, Katharine | Article in Journal | | 1978 |
| The O'Reillys and the kingdom of East Breifne | Simms, Katharine | Article in Journal | | 1979 |
| The ordinances of the White Earl and the problem of coign in the later middle ages | Empey, C. A. (Adrian)Simms, Katharine | Article in Journal | | 1975 |
| The origins of the creaght : farming system or social unit? | Simms, Katharine | Article in Book | | 2015 |
| The origins of the diocese of Clogher | Simms, Katharine | Article in Journal | | 1980 |
| The poet as chieftain's widow : bardic elegies | Simms, Katharine | Article in Book | | 1989 |
| The poet's tale | Simms, Katharine | Article in Book | NA | 2014 |
| The poetic brehon lawyers of early sixteenth-century Ireland | Simms, Katharine | Article in Journal | | 2007 |
| The political recovery of Gaelic Ireland | Simms, Katharine | Article in Book | | 2018 |
| The selection of poems for inclusion in the Book of the O'Conor Don | Simms, Katharine | Article in Book | | 2010 |
| The transition from medieval to modern in the poems of Tadhg Dall Ó hUiginn | Simms, Katharine | Article in Book | | 2010 |
| The Ulster Revolt of 1404 - an Anti-Lancastrian Dimension? | Simms, Katharine | Article in Book | | 2009 |
| Tír Eoghain "north of the mountain" | Simms, Katharine | Article in Book | | 1999 |
| Warfare in the medieval Gaelic lordships | Simms, Katharine | Article in Journal | | 1975 |
| What the dean left out : Scottish poems which have not been included in the Book of the Dean of Lismore | Simms, Katharine | Article in Book | | 2025 |
| William O'Sullivan : four appreciations | Barnard, T. C. (Toby Christopher)Hickey, ElizabethSimms, KatharineÓ Cróinín, Dáibhí | Article in Book | | 1998 |
| Women in Gaelic society during the age of transition | Simms, Katharine | Article in Book | | 1991 |
| Women in Norman Ireland | Simms, Katharine | Article in Book | | 1978 |