Composition, molecular weight, and microstructure of the "shell" polymer in core-shell structured latex particles, designed for toughening polycarbonate matrix, should be controlled for enhanced miscibility between the shell polymer and the matrix. Various "shell polymer" systems based on styrene (St) and benzyl methacrylate (BM) were synthesized. Reactivity ratios were determined for (St) and (BM). Chain transfer efficiency studies revealed the susceptibility of styrene to transfer to a chain transfer agent. Benzyl methacrylate was found to have steric and stability factors hindering its tendency to chain transfer with various chain transfer agents. Miscibility tests between P(St/BM) and polycarbonate (PC) indicated different degrees of miscibility, depending upon polymerization conditions, Factors other than molecular weight, such as branching and crosslinking, were found to play a role in the miscibility. Monodisperse poly(n-butyl acrylate) (PEA) seed latex particles of variable degree of crosslinking and particle size were successfully synthesized by batch emulsion polymerization.