The frequency dependence of the longitudinal relaxation time T 1 (v) of different liquids confined to microporous glass features a distinct difference between polar and nonpolar adsorbates. This finding is explained by weak and strong adsorption, respectively. The T 1 dispersion of polar adsorbates can be described with the aid of Levy walk statistics of bulk-mediated surface diffusion recently suggested by Bychuk and O'Shaughnessy (J. Chem. Phys. 101:772-780; 1994)