We report the graft polymerization of methyl acrylate (MA), methyl methacrylate (MMA), hydroxyethyl methacrylate (HEMA), and 2-(dimethylamino)ethyl methacrylate (DMAEMA) by atom transfer radical polymerization (ATRP) from lightly cross-linked poly(DVB80-co-HEMA) microspheres. These poly(DVB80-co-HEMA) microspheres were prepared by precipitation copolymerization and subsequently modified by reaction with 2-bromopropionyl bromide to serve as ATRP macroinitiators. MMA, MA, and HEMA were then grafted from these initiator microspheres at room temperature using CuBr/Me(4)cyclam as catalyst. The graft sites, and hence the grafted polymers, are distributed throughout the initiator microspheres. Addition of a second monomer formed grafted block copolymers, indicating that a significant portion of the first grafts could be reactivated. The final particles represent novel, high-capacity polymer supports comprised of swellable core particles carrying 5.09 and 5.18 mmol/g of grafted poly(DMAEMA) and poly(MMA-b-DMAEMA), respectively. The grafted particles were characterized using ESEM, FTIR, Coulter particle sizing, and potentiometric titration.