Pyridine ring functionalization and additional crosslinking in crosslinked poly(styrene-co-4-vinylpyridine) with various dibromoalkanes depend on the chain length of the dibromoalkane, the solvent polarity, and the molar ratio between the pyridine rings and the dibromoalkane. the effect of chain length on additional crosslinking becomes more pronounced when the good swelling solvent dimethylformamide is replaced by dibromoalkane. on the other hand, the degree of crosslinking of poly(styrene-co-4-vinylpyridine) influences both the reactivity and the additional crosslinking.