Research Libraries UK (RLUK) (formerly CURL) comprises 34 University and other research libraries in the United Kingdom and Ireland. Its aim is to increase the ability of research libraries to share resources among themselves. The holdings of these libraries provide the basis of the Copac online catalogue.
The Consortium of University Research Libraries (CURL) started in the 1980s with seven libraries (the university libraries of Cambridge, Edinburgh, Glasgow, Leeds, London, Manchester, and Oxford). By July 1996 the number of members had increased to 19, including three more in London and Trinity College Dublin. In 2011, Queen’s University Belfast joined as RLUK's newest member, meaning that all then-20 members of the Russell Group of universities were now members. Of the Russell Group's four new members that joined in 2012, all immediately became members of RLUK as well, with the exception of Queen Mary, University of London which joined RLUK in 2013.