The valence-shell electronic structure of trans-dichloroethylene has been investigated by symmetric noncoplanar (e, 2e) spectroscopy. lonization energy (IE) spectra of the valence shell (6–46 eV) have been obtained at relative azimuthal angles of 0° and 8° and compared with literature photoelectron (PE) data. The present work confirms the presence of extensive many-body features in the inner-valence region (> 18 eV), reported by previous PE studies and predicted by a literature Green's function calculation. Momentum distributions (MDs) of selected valence-shell ionic states of trans-dichloroethylene have been determined for the first time, and they are compared with MDs of the corresponding orbitals generated from ab initio self-consistent field wavefunctions of 4-31 G, 6-31 G and 6-31 ++ G ∗∗ basis sets. Good agreement between experiment and calculations is found only for a limited number of ionic states including the D(9a g ) −1 , E(2a u ) −1 , and H(7b u ) −1 states. Discrepancies are noted particularly in the lower-momentum region of the MDs of the X(3a u ) −1 , A(10a g ) −1 +B(9b u ) −1 +C(2b g ) −1 , and F(8b u ) −1 + G(8a g ) −1 outer-valence ionic states, as well as of the many-body (satellite) states corresponding to the removal of electrons from the 7a g and 6a g orbitals in the inner-valence region. The observed discrepancies in the MDs generally indicate the inadequacies of the basis sets, which are useful for further development of precise electronic wavefunction for trans-dichloroethylene on an orbital-by-orbital basis. Furthermore, the orbital assignments for the close-lying D and E ionic states have been definitively clarified by examining their characteristic MDs. Finally, MD measurements of selected satellite states above 26 eV have provided support for the hypothesis that these many-body states are dominated by the removal of electrons from the innermost valence orbital 6a g .