Self-assembly of well-defined block copolymers in solution has gained attention not only for its scientific value but also for its potential application in nanotechnology. In this study, we present a comprehensive series of synthesized block copolymers that allows conclusions to be drawn how to design micelles by ROMP with defined core-shell geometry and controlled size. We used a general route for the preparation of well-defined block copolymers by ring opening metathesis polymerization (ROMP) with "Grubbs first generation catalyst" RuCl2(PCy3)(2)(CHPh) (Cy = cyclohexyl). In a first step, we sequentially polymerized endo, exo[2.2.1]-bicyclo-2-ene-5,6-dicarboxylic acid dimethylester with endo, exo[2.2.1]bicyclo-2-ene-5,6-dicarboxylic acid di-tert-butyl ester, to obtain a high control of polymerization and complete characterization of the block copolymers. The polymers were characterized by H-1- and C-13 NMR spectroscopy, FT-IR spectroscopy, by GPC, and by DSC. By cleavage of the tert-butyl group, the polymer was transformed into an amphiphilic block copolymer. In two series of polymers, we investigated the micelle formation in ethanol by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). In the first series, the influence of the block ratio on the size of the micelle, the aggregation number, and the core-shell dimensions were investigated while the overall polymer length was kept constant. In the second series, the block ratio was fixed to 1:1 and the overall polymer length was varied, leading to direct proportionality of the micelle size to the polymer length, while the core-to-shell ratio was constant.