The heterogeneity of copolymers of styrene and divinylbenzene was investigated. The distribution of divinylbenzene units within the crosslinked copolymer yields information about the inhomogeneity of the network formed. Proceeding from the monomer reactivity ratios, the monomer compositions and from the conversion we set up histogramms of the distribution of the divinylbenzen-isomers within the formed copolymers. As a mathemathical expression of heterogeneity we used the relative variance. Possibilities to influence the heterogeneities found are discussed.