Ninety-five teleseisms and 270 local earth-quakes are used to determine three-dimensional velocity models of the crust and upper mantle beneath the New Madrid seismic zone. P wave travel time residuals from teleseisms yield a three-dimensional model of velocity perturbations in the crust and upper mantle to a depth of 156 km. Travel time residuals of local earthquakes lead to an upper crustal model which is consistent with the model for that region obtained from teleseismic data and provide details which can be related to geological structure. The local earthquake data also permit the resolution of trade-offs between the upper and lower crust which may result from the analysis of teleseismic data only. Lateral variations in velocity occur both as broad continuous or nearly continuous bands and as small-scale localized features. A band of anomalous velocities correlates in position arid orientation with a basement rift system which has been delineated from gravity and magnetic data. This band occurs as a low-velocity zone through the upper crust and uppermost mantle and may be offset beneath the branch of the New Madrid seismic zone having the most intense earthquake activity. After trade-offs with upper crustal velocities are removed, the lower crust exhibits somewhat higher-than-average velocities in the rift region. Several localized regions of high velocity in the crust inferred from teleseismic data correlate with the sites of intrusions found from gravity and magnetic data. A number of localized regions of both high and low velocities occur throughout the upper mantle with no clear-cut relation to near-surface features. ¿American Geophysical Union 1987