The nanoencapsulation of cypermethrin (CP) was carried out by miniemulsion polymerization, a convenient one-pot encapsulation technique for nanocapsules. The encapsulation was achieved by polymerization inducing phase separation within minidroplets dispersed in an aqueous phase. For nanocapsules prepared in this way, the type of surfactant and initiator, the level of the crosslinking agent or chain-transfer agent, and the monomer/CP ratio play a significant role in defining the end morphology of the latex particles. Specifically, for a styrene (St)/CP system, there were optimum levels of ionic surfactant (1.0 wt % sodium dodecyl sulfate), nonionic surfactant [0.5 wt % poly(ethylene glycol) monooctylphenyl ether], oil-soluble initiator [1.0 wt % azobis(isobutyronitrile)], crosslinking agent (1.0 wt % divinylbenzene), and a St/CP ratio of 1 : 1 for obtaining well-defined nanocapsules of CP. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012