The Gulf of California, which forms part of the Pacific-North American plate boundary, is an ideal place to investigate upper mantle dynamics in a continental rifting area. With 19 seismic stations located around the gulf, the NARS-Baja experiment (2002-2008) was designed to image its crustal and mantle structure. Here we present results of a tomographic inversion of Love and Rayleigh interstation phase velocity measurements for a radially anisotropic shear velocity model of the Gulf of California. This study confirms the overall low shear-wave velocities in the upper 200km of the mantle found in other Rayleigh wave studies, and the presence of a positive shear-wave velocity anomaly at depths of roughly 80-160km beneath the central gulf (Zhang et al., 2009). In addition, we find that the horizontal shear velocity (VSH) is generally higher than the vertical shear velocity (VSV). For the northern gulf, however, there is strong indication for VSV>VSH in the 40-60km depth range. This region also has anomalously low shear-wave velocities down to 100km depth. Combining these observations, we suggest that the low velocity anomaly and the negative radial anisotropy (VSH