We present results of temperature and magnetic field dependent resistivity &rgr;(H,T) and bulk magnetizationM(H,T) measurements on post‐annealed La0.7Ca0.3MnO3thin films that were grown via pulsed‐laser deposition. Both the resistivity and the anomalously large negative magnetoresistance peak near the ferromagnetic ordering temperature (Tc=250 K), with &Dgr;&rgr;/&rgr;0=−85% at 50 kOe. A clear correlation is found between &rgr; andMthat is described by the phenomenological expression &rgr;(H,T)∝exp[−M(H,T)/M0]. This correlation reflects the important interplay between transport and magnetism in this system, and suggests that the transport belowTcinvolves polaron hopping. ©1995 American Institute of Physics.