Individualization of single-walled carbon nanotubes (SWCNTs) in aqueous surfactant dispersions can vary greatly. We will present a new method for quantitatively assessing dispersion quality based on simple absorption spectra. In this method, the visible and short-wave infrared portions of a sample’s absorption spectrum are modeled as a superposition of two components. One component (labeled “S”) has sharp resonant features and is associated with the subpopulation of SWCNTs that are suspended as individuals or very small aggregates; the other (labeled “B”) has broad absorption features and is associated with stably dispersed materials such as carbonaceous impurities, imperfect nanotubes, and larger aggregates. Using absorption spectra from samples in various stages of purification by centrifugation or magnetic processing, we apply the method of multivariate curve resolution to extract the S and B component spectra and determine their relative contributions in samples of interest. The ratio of S to B content then provides a simple index of dispersion quality. We illustrate this new characterization method with measurements on both shear-dispersed and tip-sonicated SWCNT samples purified by three different processes: centrifugation, ultracentrifugation, and magnetic purification. We determine the dispersion efficiency of each sample preparation and find results that correlate well with those of established analytical techniques. In addition, we have further characterized the effects of these purification processes on the SWCNT length distribution (using the diffusion-based LAND method) and on SWCNT emissive properties (through variance spectroscopy). We believe that our new absorption-based method provides a practical tool for quickly assessing the dispersion quality of SWCNT samples.