  We explore the potential of the Next Linear Collider (NLC), operating in the
$e\gamma$ mode, to disentangle new physics scenarios on single $W$ production.
We study the effects related with the exchange of composite fermion in the
reaction $e\gamma \to W \nu_e$, and compare with those arising from trilinear
gauge boson anomalous couplings. We stress the role played by the initial state
polarization to increase the reach of this machine and to discriminate the
possible origin of the new phenomena.
