For the safe commercialization of nanoparticle technology, there is a need for reference materials that can be used in studiesrelated to the environmental fate of nanoparticles. This work produced metal-containing polystyrene nanoparticles with target parame-ters such as high monodispersity, tailorable size range (33–193 nm), and variable surface charge. In addition, the combination of organicand inorganic components made them detectable by all of the main analytical techniques routinely used in nanoparticle characterization,e.g., TEM, DCS, DLS, and ICP-MS (the latter when interfaced to chromatographic instrumentation). The lanthanides Gd, Dy, and Ndwere investigated as the inorganic component because of their high response when analyzed by ICP-MS, and because of their low envi-ronmental abundance. Particles were prepared by emulsion polymerization using one of two stabilizers: the nonionic surfactant PluronicF68 or the anionic surfactant sodium dodecyl sulfateVC2015 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J.Appl. Polym. Sci. 2015, 132, 42061.