The valence-shell electronic structure of trans-dichloroethylene has been investigated by symmetric noncoplanar (e, 2e) spectroscopy. Ionization 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 4-31G, 6-31G 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 transdichloroethylene 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 characteristics 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 .