[en] We report on first measurements with polarized electrons stored in a medium-energy ring and with a polarized internal target. Polarized electrons were injected at 442 MeV (653 MeV), and a partial (full) Siberian snake was employed to preserve the polarization. Longitudinal polarization at the interaction point and polarization lifetime of the stored electrons were determined with laser backscattering. Spin observables were measured for electrodesintegration of polarized ³He, with simultaneous detection of scattered electrons, protons, neutrons, deuterons, and ³He nuclei, over a large phase space