The effects of latitudinal mean wind shear on the Rossby gravity wave are investigated. It is shown that this wave stabilizes barotropically unstable mean flows near the equator. Easterly curvature expands the wave scale and helps to insure the relevance of this theorem. It is also suggested that latitudinal shear, if incorporated into a Holton-Lindzen type experiment, might act to produce a correct asymmetry in shear zone strength in the two phases of the quasi-biennial oscillation.