The Kerby Miller Papers consist of materials created or collected by Miller in the course of his research, teaching, and writing on Irish and Irish American history. The collection dates from 1958 to 2013, with the bulk of material between 1989 and 2003. The bulk of the collection consists of Miller's research files which include photocopies of material dating from the 17th through the 19th centuries, Miller's extensive notes on this material, his notes on relevant books and articles, and correspondence regarding his research. Miller's correspondents include historians, archivists, and librarians in the United States, United Kingdom, and Ireland, with historian Bruce Boling being the most frequent correspondent. Major subjects and themes present in these research files include accounts of Irish family life, pre- and post-immigration economic issues, and experiences coming to and first impressions of living in America.

Other material in the collection includes photocopies of American Loyalists' petitions to the British government during the American Revolutionary War asking for compensation for losses, explaining their political acts and affiliations, and describing their lives in America; a run of British Information Services news bulletins on various aspects of the conflict in Northern Ireland during the late 1980s and early 1990s; and reviews of Miller's work. Subjects that frequently appear in the British Information Services bulletins include religion, electoral politics, employment discrimination, paramilitary funerals, law enforcement practices or regulations, and incidents of violence attributed to various Irish republican paramilitary groups. Also included are dossiers of republican organizations including Sinn Fein, the Official Irish Republican Army (IRA), the Provisional Irish Republican Army (IRA or PIRA), and the Irish National Liberation Army (INLA). Also present are excerpts of statements made by officials or other prominent figures.