  We derive a local, gauge invariant action for the SU(N) non-linear
sigma-model in 2+1 dimensions. In this setting, the model is defined in terms
of a self-interacting pseudo vector-field \theta_\mu, with values in the Lie
algebra of the group SU(N). Thanks to a non-trivially realized gauge
invariance, the model has the correct number of degrees of freedom: only one
polarization of \theta_\mu, like in the case of the familiar Yang-Mills theory
in 2+1 dimensions. Moreover, since \theta_\mu is a pseudo-vector, the physical
content corresponds to one massless pseudo-scalar field in the Lie algebra of
SU(N), as in the standard representation of the model. We show that the
dynamics of the physical polarization corresponds to that of the SU(N)
non-linear sigma model in the standard representation, and also construct the
corresponding BRST invariant gauge-fixed action.
