The formation of vesicles in a binary blend of an amphiphilic diblock copolymer AB/homopolymer C was Studied in a dilute solution using the real space two-dimensional self-consistent field theory (SCFT), Special attention was played to the role played by the homopolymer C in controlling the vesicle formation. In the simulations, it was found that as the averaged volume fraction of homopolymer C was decreased while keeping the total averaged volume fraction of block copolymer AB and homopolymer C unchanged, there was a morphological transition from the bilayer vesicles to rod-like/circle-like micelles. The Compound vesicle structure was observed in the simulations. When the averaged volume fraction of block copolymer AB was further increased while the total averaged Volume fraction of AB and C remained unchanged, the compound vesicle structure became less favored entropically than the unilamellar vesicle structure. The effect of the degree of polymerization of the homopolymer C on the vesicle formation of the amphiphilic system was examined. By reducing the degree of polymerization of the homopolymer C to unity, the component C became a small solvent molecule immiscible with the bulk solvent. It was found that the small solvent C exerted no influence on the morphological stability of the vesicles. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.