New aeromagnetic data over Mount Shasta were analyzed to determine the bulk magnetic properties of the volcano by an inversion technique used successfully by other researchers to interpret marine magnetic anomalies over seamounts. Assuming that the intensity of magnetization is uniform and that the base of the sources is st an elevation of 2438m, we calculate by least squares a magnetization having an intensity of 1.7 A/m, an inclination of 45¿, and a declination of 51¿. This solution for the direction of magnetization is unacceptable because the volcano is geologically very young and should be magnetized in the direction of the earth's present field. The spurious direction, coupled with a positive residual anomaly over the western flank of the mountain, suggests either that this part of the mountain is magnetized more intensely or that magnetized material there extends to greater depth. Apparently, either the percentage of lava flows relative to breccias is higher within the western part of the volcano, thereby increasing its magnetization, or the Curie point isotherm rises beneath the summit. Both conclusions are geologically acceptable. Results of this study indicate that care is required in using magnetic anomalies over seamounts to obtain virtual geomagnetic pole positions. Model studies show that if the intensity of magnetization of a seamount is actually nonuniform, the calculated direction will be incorrect, and more important, the goodness-of-fit parameters will not necessarily indicate an invalid result.