Any attempt to assess archival collections of early modern Irish history documents is made difficult by the absence of adequate guides to the material. None of the main repositories has published an up to date catalogue to the documents in its custody. Indeed, many of the published catalogues date to the nineteenth or early twentieth century and are, very often, little more than a brief list of the documents in the respective collections. Information is rarely provided as to the provenance or origin of the document. Even the brief description of the document is sometimes inaccurate or misleading. The result is that research in early modern Irish history can be very exciting. The possibility of discovering unknown or unused documentation still exists. However, the absence of adequate guides can also make research very frustrating. Close scrutiny of bibliographies, particularly those in post-graduate theses, or, better still, verbal consultation with other researchers is often the easiest way to acquire up to date information on the contents of the repositories.

R. J. Hayes, Manuscript sources for the history of Irish civilisation is the most comprehensive guide to sources for all periods of Irish history. The eleven volume work which is being continued in supplementary volumes, lists most collections now in public repositories as well as many in private collections. Hayes planned this work in connection with the National Library of Ireland and his work is the best guide to manuscripts in N.L.I. It is not quite so satisfactory for other repositories of early modern material because it tended to rely on what was listed in the printed catalogues.