A two-level seismic assessment procedure for reinforced concrete frame buildings is presented. The intent of the procedure is to determine the risk, in terms of annual probability of exceedance, associated with two limit states, namely a serviceability limit state and a survival, or ultimate, limit state. The serviceability limit state is determined by elastic response calculation, but the survival limit state analysis attempts to identify the strength and ductility of the critical collapse mechanism, and hence its probability of exceedance by comparison with reference spectra. The basis for identifying the critical collapse mechanism is a modified form of capacity design principles which allows local element failure provided overall structural integrity is not jeopardized.