A molecular phenomenological model of the phenomenon of reinforcement is proposed. The model is based on the idea about the presence of a thin rubber matrix layer on the surface of active filler particles, with the said matrix being in the pseudo-vitreous state which changes to the high-elasticity state with a distance from the filler surface. In composite deformation, the most strained macromolecules do not break, but rather elongate from the pseudo-vitreous state according to the mechanism that is close to the phenomenon of forced elasticity (cold flow). The model is used to provide natural explanations of all effects characterizing the phenomenon of reinforcement (improvement of vulcanizate strength and relative elongation, higher hysteresis loss, higher rubber stiffness, and the Payne and Patrikeev–Mullins effects).