Neutralino Production with Polarized Beams in Extended Supersymmetric Models

We discuss associated neutralino production e^+ e^- --> \tilde{\chi}^0_1 \tilde{\chi}^0_2 with both beams polarized in the MSSM, NMSSM and an E_6 model. It is shown that neutralinos with a large singlino component can be produced at a high luminosity linear collider in a broad parameter range. Polarization effects in the extended models are compared over the whole parameter space where the lightest neutralino is mainly a singlino. We explain the complete different behavior of these models in some parameter regions, which may help to identify the respective supersymmetric model.