  We present a Mathai-Quillen interpretation of topological sigma models. The
key to the construction is a natural connection in a suitable infinite
dimensional vector bundle over the space of maps from a Riemann surface (the
world sheet) to an almost complex manifold (the target). We show that the
covariant derivative of the section defined by the differential operator that
appears in the equation for pseudo-holomorphic curves is precisely the
linearization of the operator itself. We also discuss the Mathai-Quillen
formalism of gauged topological sigma models.
