Hydrophilic poly(dimethyl aminoethyl methacrylate) (PDMAEMA) copolymer was obtained by suspension polymerization using 2,2'-azobisisobutyronitrile as an initiator, and by emulsion polymerization using 2,2'-azo-bis(2-amidinopropane)-2HCl (V-50). The influences of reaction parameters on the particle size and size distribution were investigated. For suspension polymerization, these included the concentrations of ethylene glycol dimethacrylate (EGDMA) crosslinking agent, ethyl acetate (EA), and Na2SO4, electrolyte, the types of comonomer [methyl methacrylate (MMA) or styrene (ST)], solvent (EA or acetone), and stabilizer [poly(oxyethylene nonylphenylether) with 23 units of ethylene oxide (PEO23) or polyvinylpyrrolidone K30 (PVP)], polymerization temperature, and ST content in the comonomei feed. For the emulsion polymerization, the reaction parameters included the concentration of cetyltrimethyl ammonium chloride and V-50, and types of initiator [V-50 or potassium persulfate] and crosslinking agent [EGDMA or divinylbenzene]. The solubility of hydrophilic comonomers in the aqueous phase was a key factor for the stability and morphology of the PDMAEMA particles. It was found that the stable uncrosslinked PDMAEMA latex could be prepared by charging 20 wt % (based on the monomer) of ST. Moreover, the crosslinking agent significantly affected the coagulum in both the suspension and the emulsion polymerizations.