A series of composite polymer nanoparticles was prepared from poly(N-vinylcarbazole) (PVK) and poly(2,5-bistriethoxy-p-phenylene vinylene-alt-phenylene vinylene) (BTEO-PPV-alt-PPV). The nanoparticle sizes were measured to be in the range of 50-80 nm with transmission electron microscopy. The photoluminescence intensity of PVK decreased with the content of BTEO-PPV-alt-PPV increasing in the composite polymer nanoparticles because the excited states in PVK were quenched by BTEO-PPV-alt-PPV. The emission from BTEO-PPV-alt-PPV was enhanced in the composite polymer nanoparticles because of energy transfer from PVK to BTEO-PPV-alt-PPV for excitation at the absorption maximum of PVK. The energy-transfer efficiency was markedly improved in the composite polymer nanoparticles versus the composite polymer films according to emission spectral analyses. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 3340-3344, 2010