This invention relates to a composition comprising microcapsules suspended in an aqueous media, said microcapsules comprising a water immiscible material contained within an encapsulating wall of polymeric material, wherein the aqueous media contains a stabilizer comprising an anionic polymer mixture comprising a first sulfonated polystyrene polymer and a second sulfonated polystyrene polymer wherein the ratio of the weight average polymer molecular weight of the first polymer to the second polymer is greater than 2. It further relates to an imaging element comprising said microcapsules.