This article reports on a new phenomenon: The presence of a compatibilizer accelerates the melting/plastification of an immiscible polymer blend during melt blending. The increase in the rate of melting as a result of the addition of a compatibilizer is believed to be one of the important factors responsible for the fact that the morphology of compatibilized blends develops much faster than that of their uncompatibilized counterparts. To substantiate the above statement, blends based on polypropylene (PP) and polyamide 6 (PA6) were used as model systems. The compatibilizer was a graft copolymer (PP-g-PA6) with PP as the backbone and PA6 as grafts. Its presence in a PP/PA6 blend accelerated the rate of melting of the PA6. This effect was observed only when the compatibilizer itself was molten and migrated to the interfacial layer between the PA6 and PP phases. It is likely that the presence of the compatibilizer increased the chain entanglements at the PP and PA6 interface and consequently reduced the thermal resistance of the interfacial layer. Detailed mechanisms are discussed.