The coil-to-globule transitions of fractionated poly(N-isopropylacrylamide) chains attached to electrosterically stabilized polystyrene latex particles were studied for molecular weights ranging from 3 10 5 to 2 10 6 . The shapes of the transitions proved to be a sensitive function of the polymer molecular weight: the component of the transition that occurred under better than θ-solvency conditions increased significantly (from 30 to 80%) as the molecular weight was decreased by an order of magnitude; concomitantly, the component that occurred under worse than θ-solvency conditions was substantially decreased. Studies carried out with 1 3 C NMR supported the hypothesis that these two types of transitions were phenomenologically different. The transitions in worse than θ-solvents can be attributed to the strong attractive binary interactions that characterize worse than θ-solvents, whereas the transitions in better than θ-solvents arose from the weaker attractive many-body interactions, i.e. n-clustering. Simple scaling law considerations imply that the component of the coil-to-globule transitions arising from n-clusters should decrease with increasing molecular weight of the interfacial polymer, in conformity with the experimental data.