In this letter it is shown that high resolution Fe Kβ excitation spectra can be used to separately probe empty spin-up and spin-down final states. Spin-selective x-ray absorption spectra were obtained by selectively monitoring different regions of the Kβ emission. The fluorescence was excited with monochromatized synchrotron radiation and analyzed using a spherically bent Ge(620) crystal. Spin–polarization was demonstrated by showing that the 1s→3d transition at the Fe K edge is seen with Kβ1,3 detection, but missing in the excitation spectrum using Kβ′ detection. The spin–polarization is also confirmed by ligand field atomic multiplet calculations that reproduce the Kβ spectra. Calculations are presented showing the applicability of spin–polarized Kβ detection to nearly all first transition metal ions.