Specitication of response spectra is a standard practice in seismic design and qualification. The design spectra are generally the curves of maximum response acceleration levels as functions of periods of single degree-of freedom systems for various values of damping. In literature several authors have addressed themselves to establish smooth design response spectra through statistical methods. Newmark, Blume and Kapur¹ have developed smooth design spectra with the help of thirty-seven earthquake records, recorded on different soil conditions. On the other hand, Mehraza and Seed, Ugas and Lysmer have established design spectra specific to certain soil conditions. Generally, the design spectra are smoothened to account for variations due to steep peaks and valleys. Prior to smoothing, the records are normalised with respect to their peak ground motion param- eters. Smooth design response spectra (SDRS) are also specified at floor levels in the form of floor response spectra for design and qualifications of equipments in power plants. The SDRS, due to their simplicity, are very appealing to the design engineers. These are used commonly to find equi- valent static forces or are used in estimating responses through the SRSS approach. Another very important application is in generating spectrum compatible accelerograms to be used in direct time-history response analysis. In the later case, it is now well recognized that not all spectra are internally consistent to produce a compatible accelerogram For a single spectrum, admissible Levy and Wilkinson point out that every spectrum need not have an time-history. Scanlan and Sachss have observed that it is inconsistent to simultaneously prescribe simplified spectra for several damp- ings that would have a single time-history compatible with all of them. different However, at present what constitutes conistency between spectrum at when damping leveis is not clearly known. The same question arises one has to estimate from a given spectrum the spectrum for another value and damping of damping. The dependence of the response spectra on frequency can perhaps be obtained analytically for simple excitation. But for real earthquake accelerograms, this can be obtained only through data analysis. With this in view, in the present study, a set of sixty-six earthquake records are selected for evolving. a reference spectra and to compute inter-damping scaling relationships.