This paper describes the supramolecular assembly of arborescent (dendrigraft) copolymers in solution. The dendritic copolymers remained as unimolecular (nonassociated) micelles in toluene at temperatures above the critical self-assembly temperature (cst) but aggregated into supramolecular structures with a diameter of a few micrometers below the est. Small-angle neutron scattering (SANS) measurements in toluene revealed that the P2VP shell of the unimolecular micelles was swollen above the cst. The supramolecular aggregates obtained below the cst had a spherical topology and a relatively uniform size according to electron microscopy analysis. The temperature-responsive self-assembly process was fully reversible. The cst varied with the copolymer concentration and shifted to higher temperatures as the length of the P2VP chains in the shell increased. The self-assembly mechanism reported provides a path to new types of "smart" supramolecular structures.