Viscoelastic behavior is advantageously displayed using the relaxation spectrum, because its distinct peaks correspond to processes centered at definite relaxation times. Quantitative characterization then becomes possible using parameters for strength, location, spread, and rate of decay, in the mathematical functions representing the peaks. Use of symmetric bell-shaped functions that occur in statistical theory makes a practical method possible, for solving the generally ill-posed inverse problem of finding the relaxation spectrum, using spreadsheet software. The starting data are observations of complex modulus from dynamic mechanical analysis (DMA). Time-temperature superposition allows the result to be displayed as a temperature sweep, at some reference time. From data in the literature, referred to a time of 1000 s, a poly(n-octyl methacrylate) fraction can be characterized with three peaks, at 55°C, −42°C and −56°C, and a commercial polystyrene with two peaks, at 122°C and 108°C. Published data for rubbery copolymers and their blends with isotactic polypropylene give spectra with one peak for the terminal zone, at 21°C to 35°C, depending on the material, when referred to time 1 s. For the immiscible blend an additional peak appears at 93°C, corresponding to phase separation; from its location one can estimate 50 Pa for the ratio of interfacial tension to droplet radius. Random errors in the DMA data degrade the precision of the method, so that typically a 5% noise level in the complex modulus would cause peaks separated by 8°C to become merged.