Adsorbents and methods for the adsorptive separation of meta-xylene from a mixture containing at least one other C.sub.8 aromatic hydrocarbon (e.g., a mixture of ortho-xylene, meta-xylene, para-xylene, and ethylbenzene) are described. Suitable adsorbents comprise sodium zeolite Y having an average crystallite size from about 50 to about 700 nanometers. The adsorbents provide improved separation efficiency, which may be associated with a higher meta-xylene mass transfer rate and/or other beneficial effects. Exemplary desorbents for use in the process may comprise toluene, benzene, or indan.