The micellization properties of two star block copolymers, of the type (PSPI)(8), where PS = polystyrene and PI = polyisoprene, with PI inner blocks, were investigated, in dilute solutions in two selective solvents for the PS block, namely, dimethylacetamide (DMA) and ethyl acetate (EA), by means of static and dynamic light scattering and viscometry. For comparison purposes the linear diblock arms of the star copolymers, as well as a linear diblock with composition and molecular weight similar to those of one of the stars, were also studied. The carefully designed set of copolymers, as well as the different solvent selectivity toward the two blocks, allowed the elucidation of differences in behavior concerning both the structure of the micelles formed and the kinetics of the micellization process. In DMA the star block copolymers were found to form micelles of smaller size, having lower aggregation number and shorter coronas compared to the diblock case. In comparison with the diblock arm case, star block copolymers formed micelles of essentially the same structure. Star and linear copolymers of low molecular weight formed unimolecular micelles in EA, whereas multimolecular micelles were observed for the higher molecular weight star and linear copolymers. Micelle-unimer equilibrium could be shifted to either side by changes in temperature. Kinetics of micelle formation in EA were faster for the star block case.