Polystyrene microspheres ranging in diameter from 3 to 10 mu m were prepared in alcoholic media by dispersion polymerization of styrene in the presence of a methacrylic acid/ethyl acrylate 1:1 statistical copolymer (Eudragit) as the stabilizer precursor. The effects of the initial Eudragit and free radical initiator concentrations on the microsphere dimensions, the microsphere size distribution and surface functionality were investigated. The particle dimensions were found to increase with increasing initiator concentration and decrease with increasing steric stabilizer precursor concentration. The percentage Eudragit in the microspheres was found to increase with the stabilizer precursor concentration and decrease with the initiator concentration. The resulting double-shell microspheres, with specific surface functionalities, are promising as tailor-made supports for biocatalysts.