The effects of alkyl chain length of homologous alkyl sulfate surfactants ranging from C8 to C14 on the diffusion behavior of both the surfactant and gelatin have been investigated by pulsed-gradient spin-echo NMR spectroscopy. Changes in the diffusivity of the surfactant can be rationalized in terms of a two-state model consisting of gelatin-bound micelles in equilibrium with freely diffusing unimeric surfactant. A minimum in the diffusivity of gelatin is observed when the binding of surfactant amounts to about 1 micelle/strand. The depth of this minimum increases with the chain length of the surfactant. These effects are explained in terms of micelle-mediated transient cross-links as proposed by Greener et al. (Macromolecules 1987, 20, 2490). The effective strength of the cross-links is a decreasing function of the number of micelles/strand because of the electrostatic repulsion between the micelles; the strength increases with an increase in the size of the micelles.