Conjugated polymeric semiconductors are established to be effective donors upon photoexcitation. In blends of these polymers with Buckminsterfullerene, C60, the latter acts as a strong electron acceptor upon illumination. Lately the research on semiconducting polymers has put enhanced emphasis on the development of optoelectronic devices made from these polymer blends. Especially the device production demands good processability of the working material. A complete new approach to improve the processability of semiconducting polymers in their incorporation into host matrices formed by conventional polymers such as polyethylene (PE) or polystyrene (PS). We have characterized the linear optical properties of several guest-host systems by absorption and luminescence measurements and probed the excited states by photoinduced absorption measurements. The composition of the blend strongly influences the interaction between the conjugated polymer and the C60. In blends with PS as matrix and a soluble polyphenylenevinylene derivative as conjugated polymer we found strong luminescence quenching upon adding C60, in contrast to a system with a PE matrix.