The residual gravity anomaly assiciated with Meteor Crater, Arizona, which attains a maximum negative amplitude of 0.6 mGal, is attributed to a breccia lens 225 m thick beneath the center of the apparent crater floor. The lens is in general radially symmetric with only minor irregularities, particularly in the southern half of the crater. No definitive evidence was found for a dense meteoritic body in the crater vicinity. The crater is surrounded by a negative gravity anomaly due to low-density rim debris, uplifted and fractured bedrock, and possibly an underlying fractured zone extending about one crater radius out from the rim crest and dipping in the crater. A magnetic minimum with a maximum negative amplitude of approximately 20 &ggr; is coincident with Meteor Crater. The most probable source of this anomaly is the alteration, by impact, of the remanent magnetization of the underlying formations, particularly the Supai, within and beneath the breccia lens.