Reinforced concrete flat-plate construction is a popular building type because of the simple formwork required for construction and the clearance that is provided for mechanical and electrical equipment. During the period 1950 through 1980, buildings using the flat-plate for the lateral-force resisting system have been built in seismic regions. The displacement response of these structures during credible earthquakes results in concentrations of shear, flexure, and torsion at the slab-column connection that can lead to brittle failures. Proper evaluation of this response is a matter of importance for the economy and for public safety. Included in this study is the (a) construction, instrumentation, and cyclic lateral load testing of a full-scale three-story flat-plate structure, (b) development of analysis methods to determine the limiting strength and drift capacities of flatplate structures, and (c) the definition of a hysteresis model to estimate the dynamic response of the flat-plate structure subjected to selected strong ground motions.