The energy transfer in a blend of electroluminescent conjugated polymers, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and conjugated-nonconjugated multiblock copolymers (CNMBC), was investigated. Energy transfer from CNMBC to MEH-PPV leads to the enhanced emission of MEH-PPV. Fluorescence decays also support this energy-transfer process, which is faster than radiative and nonradiative decays. PL and EL quantum efficiencies of the blended polymer were enhanced as the relative content of CNMBC was increased, and surprisingly, 500 times improved EL efficiency was observed for some blend ratios. These results provide further insight into the photophysics of conjugated polymers and the improvement of the electroluminescence quantum efficiency using the blended polymer systems.