Near-monodisperse, submicrometer-sized, colloidally stable polyacid particles containing phosphate groups were synthesized by free radical dispersion polymerization of acid phosphoxy polyoxyethylene glycol monomethacrylate in isopropanol using poly(N-vinylpyrrolidone) as a steric colloidal stabilizer. Dispersion copolymerizations with divinyl crosslinking comonomer were also useful to synthesize crosslinked polyacid particles without any coagulum.