We have observed, for the first time, that when the initial chain conformation changed from coil to globule, the association of linear poly(N-vinylcaprolactam-co-sodium acrylate) chains could gradually change from a reaction limited to diffusion limited process, reflected in a change of the fractal dimension of the resultant aggregates from similar to2.5 to similar to1.6. Such an influence of the initial chain conformation has been overlooked in past studies of the formation of the mesoglobule phase in a dilute heteropolymer solution.