Abstract | The Global Earthquake Model (GEM) has commissioned the preparation of analytical seismic vulnerability guidelines for loss assessment of highrise buildings. The guidelines attempt to provide a practical method to assess the relationship between ground shaking and repair cost for a class of buildings, in face of the time, skill and computational challenges posed by a class rather than a single structure. An example is presented that reflects a class of modern (post-1980) highrise reinforcedconcrete moment-frame (RCMRF) office buildings in the western United States. Seven characteristic “index” buildings were selected through moment-matching, so as to represent all important aspects of the class. Each is modeled and analyzed through Incremental Dynamic Analysis (IDA). To remove issues of sufficiency without performing record selection, an extensive comparative study of intensity measures (IMs) was undertaken. Scalar IMs, defined as the geometric mean of spectral acceleration values at adjacent periods, were found to be satisfactory. Then, for each of the seven index buildings, poor, typical, and superior-quality variants were considered to establish the seismic loss and its ratio over replacement cost new in each case. The end product is a high quality set of vulnerability curves, whose weighted moments are taken as the uncertain vulnerability function of the class.