Poly(styrene-divinylbenzene beads, preirradiated in air, were graft-copolymerized with mixtures of maleic anhydride and styrene. A detailed study of grafting was made under various reaction parameters. The succinic anhydride residues of a sample of copoly(styrene-divinylbenzene)-g-poly(maleic anhydride-styrene) with 111% grafting were chemically transformed into N-hydroysuccinimide (Resin I) and N-bromosuccinimide (Resin II) residues. The esters derived from Resin I (analogous to the N-hydroxysuccinimide esters) were good acylating agents and their use was explored for the synthesis of peptides. Resin II was used for the bromination of benzylic substrates. The spent resins were found to be reusable without much loss to their capacity.