A seismic P wave velocity and bulk density model of the crust of the western Transverse Ranges of California along a north-south profile near the city of Santa Barbara shows south to north crustal thickening and appreciable lateral inhomogeneity within the crust. The seismic model is developed by ray tracing based on data from a land-sea refraction experiment, Pn arrivals from regional earthquakes, and near-vertical arrivals from teleseisms. The density model is based on published gravity data (Bouguer on land and free air at sea). The model extends to the known oceanic lithospheric structure west of the southern California Borderland, providing a boundary condition for modeling crustal thickness. The Borderland crust south of the western Transverse Ranges is 23 km thick, and the Coast Ranges crust to the north is 31 km thick. A low-density, low-velocity feature associated with deep Neogene sediment in the Santa Barbara Channel extends to depths greater than 10 km. A local high-density, high-velocity feature is associated with exposures of Mesozoic mafic crystalline rock on Santa Cruz Island. Low-density and velocity material is resolvable to 5-km depth south of the East Santa Cruz Basin fault. ¿ American Geophysical Union 1987