A broad-based program for studying hardware, software and human factors affecting information retrieval system performance is described. Using EUREKA, a minicomputer-based retrieval program, studies of user adaptation to an on-line system, search strategy development and use of special features are in progress. Performance comparisons are made between machine-assisted users and those using conventional printed materials. Concurrently, special-purpose retrieval hardware is being designed, and one prototype system is under construction. To support and supplement this work, various modeling and simulation studies are also in progress.