Resolution of complex gamma-ray spectra obtained with NaI(Tl) detectors is a means to fast, accurate determinations of radionuclides. Detection limits, a function of counting statistics, can be extended by use of preferential counting techniques and simple chemical separations. The method is applicable to the determination of radionuclides singly and in complex mixtures. Two experiments are described to demonstrate the flexibility of spectral resolution. A table is included to show the correlation of data obtained by spectral resolution and by conventional radiochemical analysis. Spectral resolution simplifies the analysis of complex mixtures and reduces the cost of analysis with no sacrifice of the quality of the data.