The writing of labour history depends on the survival and preservation of source material. Labour history societies in Scotland, England and Australia have played a major role in efforts to preserve the records of the labour movement. This article traces the origins of labour history archives in those countries and compares their development over the last few decades. It outlines the locations and strengths of the main collections and the variety and importance of other repositories, including regional collections. The authors discuss how to approach the search for sources and consider several national and international collaborative projects designed to facilitate access to finding aids and catalogues. They also discuss issues affecting the accessibility of labour history archives today, including legislative considerations and the challenge of electronic records. The article illustrates how archivists and those working with labour history collections can assist historians in the quest to produce truly comparative history.