Core-shell particles were prepared in which crosslinked polystyrene formed the core and the shells were of poly(styrene-g-N-isopropylacrylamide). The particles were successfully prepared by copolymerizing styrene with an N-isopropylacrylamide macromonomer in the presence of crosslinked polystyrene latices. Two series of core-shell particles have been prepared. In the first series the core and shell polymerizations were affected by the hydrogen peroxide/FeCl2 redox couple. Thus these particles are free from surface charges. Another series of particles was prepared with potassium persulfate as initiator so that these particles possessed sulfate surface end-groups. After purification, the sulfate functional particles were colloidally stable. Particles without surface charge were less stable. This was reflected in the larger particle sizes of the non-charged particles. Lightly grafted non-charged particles coagulated on removal of surfactant.