A simple and modular synthetic approach, based on miniemulsion polymerization, has been developed for the fabrication of composite polymer-metal nanoparticle materials. The procedure produces well-defined composite structures consisting of gold, silver, or MnFe2O4 nanoparticles (similar to 10 nm in diameter) encapsulated within larger spherical nanoparticles of poly(divinylbenzene) (similar to 100 nm in diameter). This methodology readily permits the incorporation of multiple metal domains into a single polymeric particle, while still preserving the useful optical and magnetic properties of the metal nanoparticles. The morphology of the composite particles is retained upon increasing the inorganic content and also upon redispersion in organic solvents. Finally, the ability to tailor the surface chemistry of the composite nano-particles and incorporate steric stabilizing groups using simple thiol-ene chemistry is demonstrated. (C) 2010 Wiley Periodicals, Inc. J Polyrn Sci Part A: Polym Chem 48: 1594-1606, 2010