This article examines the history and development of the Public Record Office of Northern Ireland (PRONI) between 1922 and 1948, from the destruction of the Public Record Office of Ireland (PROI) in Dublin to the retirement of David Alfred Chart, a man who played a pivotal role in the development of PRONI. Drawing on extensive archival sources, the article qualitatively analyses the administrative history of PRONI. It explores the legislation underpinning PRONI, the early establishment and development of the record office, the means by which the institution acquired records, the expansion of the record office in the 1930s and the work of the institution during World War Two (WWII). The article argues that PRONI had a clear legislative framework, scope, and mandate for its Deputy-Keeper, factors that enabled the archive to develop quickly and to thrive. It also argues that the energy, enthusiasm, and hard work of Chart was vital in the successful development of the institution. Using PRONI as a case study, the findings of this article contribute more broadly to our understanding of the establishment and development of national archives internationally, the challenges employees face, and the factors that contribute to the successful development of a new national archive.