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��^0_1 \tilde��^0_2 and the subsequent decay \tilde��^0_2 --> \tilde��^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.

6 pages, LaTeX, 8 eps figures, uses sprocl.sty which is included; contribution to the proceedings of the International Workshop on Linear Colliders, Sitges, Barcelona, Spain, April 28 - May 5, 1999; reference and acknowledgment added