This article examines the effects of dispersed phase concentration, processing apparatus, viscosity ratio, and interfacial compatibilization using an SAN-amine compatibilizer on the morphology of blends of bisphenol A-polycarbonate (PC) with styrene-acrylonitrile (SAN) copolymers. For uncompatibilized blends, the dispersed phase particle size increased significantly with SAN concentration, and was found to exhibit a minimum at a viscosity ratio of approximately 0.35 for a fixed concentration of 30% SAN in the blend. Although the morphology of uncompatibilized PC/SAN blends mixed in a Brabender mixer, single-and twin-screw extruders were quite similar, the twin-screw extruder produced significantly finer morphologies in blends containing SAN-amine. The average particle size for blends compatibilized with the SAN-amine polymer was approximately half that of uncompatibilized blends and was relatively independent of viscosity ratio and dispersed phase composition.