This invention is based upon the discovered that crosslinked core-shell particles can be used as a filler in low cost emulsion styrene-butadiene rubber (ESBR) with excellent results being attained. In fact, such core-shell particle filled ESBR exhibits performance similar to silica filled solution styrene-butadiene rubber (SSBR) in terms of dynamic response, Payne effect, rebound and tan .delta. at 0.degree. C. and 100.degree. C. The utilization of such crosslinked core-shell particles in rubber compounds offers the additional advantage of weight reduction since the core-shell particles are significantly less dense than carbon black or silica fillers. The use of the crosslinked core-shell polymers of this invention in rubber formulations in place of silica also offers the advantage of not needing any expensive silane coupling agents to attain required levels of polymer/filler interaction. Accordingly, no silane coupling agent is used in the rubber compounds of this invention which leads to reduced cost. Cost can be further reduced by virtue of the fact that compound mixing conditions can be substantially relaxed as compared to mixing silica containing rubber formulations. The present invention more specifically discloses A rubbery composition which is comprised of (1) an emulsion styrene-butadiene rubber, (2) carbon black, and (3) core-shell particles, wherein the core-shell particles are comprised of (a) a crosslinked elastomeric core comprised of repeat units that are derived from at least one diolefin monomer, and (b) a polymeric shell which is derived from at least one vinyl aromatic monomer.