Magnetic, structural and transport measurements on granular [La 0.7 Sr 0.3 MnO 3 ] 1−x [Insulator] x pellets were carried out. The system displayed a conduction threshold at x>30%, i.e., for a La 0.7 Sr 0.3 MnO 3 volume fraction XFM∼70%. Beyond this value, the resistivity increased steeply, setting up a rather insulating behavior. Nevertheless, the maximum enhancement in magnetoresistance was observed at a concentration x=xc∼10% at low temperatures and ∼20% at room temperature. This result was demonstrated to be independent of the applied magnetic field strength. The observed magnetoresistance enhancement seemed to be consistent with the disorder-driven amplification of spin-dependent transport at the structural boundaries of the mixture, due to the presence of the insulating material within the ferromagnetic matrix.