Novel microparticles of poly(ethylene oxide) (PEO)-grafted cationic polyacrylamide were prepared through the free-radical tetrapolymerization of acrylamide, acryloyloxyethyl trimethylammonium chloride (DAC), PEO macromonomer, and N,N'-methylene bisacrylamide in an inverse microemulsion. The effects of the DAC content and the PEO chain length and content on the diameter and distribution of the microparticles were studied. Highly effective retention aids were obtained in retention experiments with fibers. (c) 2006 Wiley Periodicals, Inc.