Real‐time, or on‐line computer control of circulation records, is being studied at The Queen's University of Belfast. This paper describes in simple terms the real‐time method of operating a computer and suggests a library model based on this. Two experimental real‐time computer library situa‐tions are described: at Massachusetts Institute of Technology, M. M. Kessler is operating an indexing system which is capable of possible expansion to library catalogue size, while at the IBM Los Gatos Library an experimental ordering and cataloguing system is operating. Plans for the circulation control experiments at Queen's University, Belfast, are presented and discussed. They provide for interrogation of the loan file to provide information about any book on loan, and for automatic recall and reserve routines. The experiments will also include cost analyses.