The pH dependence of the stability of the clathrin coat structure of coated vesicles and baskets has been evaluated by light scatter and sucrose gradient centrifugation. The influence of several lyotropic (Hofmeister) salts has also been studied by the same methods in order to distinguish between electrostatic and hydrophobic contributions to the free energy of clathrin association. In accord with the Hofmeister ranking, sulfate stabilizes whereas perchlorate destabilizes coat structure. Both types of interactions contribute to the stability of the coat structure in coated vesicles and baskets since both ionic strength and Hofmeister effects have an important influence. The properties of clathrin in both types of particles are similar, with the coat being slightly more stable in coated vesicles than in baskets.