We have fabricated semiconducting polymer nanoparticles from poly[2-methoxy-5-(2'-ethyl-hexyloxy)-p-phenylene vinylene] (MEH-PPV), poly(N-vinylcarbazole) (PVK), and their blends via a reprecipitation method. When excited by the peak wavelength of the PVK absorption band, the polymer nanoparticles show enhanced emission from the MEH-PPV component. The emission color can be tuned from blue to orange-red by varying the content of the MEH-PPV component in the composite nanoparticles. Since the PVK nanoparticles have a wide photoluminescence (PL) spectrum, which overlaps well with the absorption band of the MEH-PPV nanoparticles, the PL enhancement is considered to be due to F6rster energy transfer from PVK to MEH-PPV in the composite nanoparticles. Time-resolved fluorescence examinations confirm our assignment. These polymer nanoparticles are expected to have potential applications in ftiture nano-optoelectronics. (c) 2007 Elsevier B.V. All rights reserved.