The influence of block copolymers (BCP) and interfacial reaction on the deformation of 30-100 mu m polymer drops inside an immiscible polymer matrix was visualized in a parallel plate, counterrotating apparatus. Symmetric diblock copolymers were blended into polypropylene (PP), poly(methyl methacrylate) (PMMA), and polyethylene (PE) homopolymers. These were dispersed as drops in a polystyrene (PS) matrix. Addition of BCP significantly increased the amount of area the deforming drop generates when subjected to simple shear flow. Polymers with terminal amine groups (PMMA and PS) were coupled with maleic anhydride functional PS and PE. This reaction results in the formation of graft copolymer at the interface. These reactive pairs appear to be even more effective than BCP at generating interfacial area. The enhancement in area may be attributed to reduction in interfacial tension or to reduction in slip, but more likely a combination of both and a gradient in interfacial tension.