Simulated annealing, a non-linear global search algorithm, is used to invert teleseismic P-wave slowness and azimuth data for crustal velocity structure. Synthetic tests show that simulated annealing is able to locate low P-wave velocity zones with reasonable accuracy in space, and recovers almost 70% of the target velocity perturbations. Testing suggests that significant results can be obtained with as few as two stations. Inversion of ray direction data from Long Valley caldera finds an asymmetrical low velocity zone beneath the resurgent dome at 8km depth, having a perturbation of -25% from the background. This zone extends to the east and south to depths of at least 24km, with a perturbation of about -10%. These features generally agree with previous results from teleseismic travel-time inversion and forward modeling of ray direction, and are probably associated with the residual Long Valley caldera magma chamber. ¿American Geophysical Union 1995