This project is supported under NSF Announcement No. 90-23, "Repair and Rehabilitation Research for Seismic Resistance of Structures." The object of the research is to determine how masonry infill panels resist story shears during earthquakes. The focus of the investigation is on the tolerable amount of lateral drift that existing infills can resist within their plane before significant damage occurs. In addition, the stability of damaged infills is to be examined by loading cracked panels normal to their plane. Repair measures will be developed that will enhance transverse flexural strength. A series of full-scale specimens are to be constructed and tested. Each test structure will be a one-story masonry infill panel surrounded by a one-bay reinforced concrete frame. Horizontal forces will be applied at static rates, but will be cycled in a representative sequence of small and large amplitudes. Variables of the test series will include the type of masonry unit (clay brick or concrete block), the type of mortar, the strength and stiffness of the frame and the type of infill repair method. This project is part of a collaborative research effort which combines fundamental studies by an academic institution and a professional engineering firm. Together they represent a common effort for the implementation of research results.