Filled polymers exhibit a diverse range of rheological properties, varying from simple viscous fluids to highly elastic solids with increasing filler volume fraction, φ.The effect of filling on rheology is well-known in the range of small φ where the reinforcement could be attributed to hydrodynamic effects caused by the solid inclusions in the melt stream.For high φ where direct particle contacts dominate the deformation, a straightforward solution of hydrodynamic equations is difficult and theoretical models based on the realistic structural ideas are still missing so far.The liquid-like to solid-like transition at the low-frequency zone has been ascribed to the slowdown of chain relaxation due to polymer adsorption on the surface of particles, the long-lived chain bridges between the particles, the jammed network of interacting particles at low and intermediate φ, or the colloidal and frictional interactions as well as breakdown of lubricated indirect contacts between particles at φ high enough.We will show, however, the so-called liquid-like and solid-like behaviors share the common mechanism, in the framework of a proposed "two phase model" applied to linear dynamic rheology of polymer melts filled with a wide range ofnanosized fillers.