  We show that the availability of longitudinally polarized electron beams at a
500 GeV Linear Collider would allow, from an analysis of the reaction e^+e^-\to
W^+W^-, to set stringent bounds on the couplings of a Z' of the most general
type. In addition, to some extent, it would be possible to disentangle
observable effects of the Z' from analogous ones due to competitor models with
anomalous trilinear gauge couplings.
