Strong-motion accelerograms from the May 1980 Mammoth Lakes earthquake sequence are used to support the technique of estimating near-source ground motion by the summation of existing records. An SMA-1 record recovered 3 km from the epicenter of the first magnitude (ML) 6 earthquake in the Mammoth Lakes sequence (25 May, 16:33:44 UTC) is simulated by the summation of records from later events. The source-time history on which this summation is based comes from a study of the teleseismic P waves. The summation method has several distinct advantages: it is easy to apply; inexpensive (costly wave-propagation codes are not needed); and source-to-receiver propagation effects are automatically included. The method, however, requires a good data base from which to perform the summation.