Monocrystals of simple and mixed rare earth scandates are synthesized. The absorption and luminescence spectra of neodymium in mixed scandates of yttrium and gadolinium are investigated, especially the nature and the structure of arising activator centres. It is shown that the scandium ion may partially replace the crystallographic sites that are characteristic of RE ions. Diagrams of neodymium energy levels in mixed scandates are plotted basing on the performed spectroscopic investigations. At 77 and 300 K a stimulated emission phenomenon is obtained.