This paper extends a concentration-swing frequency response method to examine mass transfer rates and concentration dependence for adsorption of condensable vapors in single adsorbent particles. The new approach can be used to measure equilibria and rates on new adsorbent materials, for which only a small research sample may be available. Mass transfer mechanisms can be easily identified. We consider some common systems as examples of implementation of the method. The adsorption kinetics of water and hexane in BPL activated carbon and water in silica gel are determined at several different concentrations. The mechanism that best describes the adsorption of water in BPL activated carbon is nanopore diffusion, with the diffusivity having a clear minimum near P/Po = 0.5. The concentration dependence of the diffusion data is not described well by the Darken relationship. Both nanopore diffusion and the Glueckauf linear driving force model can be used to describe the diffusion of hexane in BPL activated carbon, and the dependence of the diffusivity on concentration can be qualitatively described using the Darken relationship. The diffusion of water in silica gel cannot be described by the nanopore diffusion model and is best characterized by the linear driving force.