  We study polarization and spin correlation effects in the MSSM and in
extended supersymmetric models at an e^+e^- linear collider with polarized
beams. The production of light neutralinos e^+ e^- --> \tilde\chi^0_1
\tilde\chi^0_2 and the subsequent decay \tilde\chi^0_2 --> \tilde\chi^0_1 e^+
e^- including full spin correlations is compared in three supersymmetric
models: MSSM, NMSSM and an E_6-inspired model with an additional U(1)' gauge
group. It is shown that polarization and spin effects can lead to a complete
different behavior of these models. Finally, the dependence of the cross
section and the decay angular distribution on the gaugino mass parameter M_1
for polarized beams is briefly outlined.
