The importance of the sequence distribution in a copolymer that is used as an interfacial modifier relative to the importance of its composition polydispersity is examined. Using Monte Carlo simulation, the microstructure of a copolymer is shown to have a greater influence on the ability of a copolymer to effectively strengthen a biphasic blend than the compositional polydispersity. Correlation to experimental studies and implications of these results on the design of polymeric surfactants are also noted.