Results of a series of experiments are presented on seismic performance of unreinforced masonry infill panels. The object of the investigation is to examine the loss of out-of-plane strength with in-plane damage. Both brick and concrete block infill panels are subjected to a regime of static, in-plane load reversals which result in extensive cracking of the infill. Then, the same panels are subjected to transverse pressures using an airbag until ultimate strengths are reached. Cracked panels are then repaired, and subjected again to transverse pressures to examine the effectiveness of a strengthening scheme. This research-in-progress paper presents some preliminary test results that suggest the amount of out-of-plane strength loss that is possible with in-plane cracking, and to infer what the potential of a particular repair method may be.