The cause of the shifts in quadrupole coupling constants between the gas and solid phases and between equivalent positions in a symmetrical polysubstituted molecule is investigated. An assignment of quadrupole resonance frequencies to positions in the unit cell of 1,3,5‐trichlorobenzene is made on the basis of the calculated electric field. There is agreement with the true assignment and with the magnitude of shifts due to external electric fields. It is concluded that shifts in the resonance frequencies of nuclei at equivalent positions are due mainly to crystalline electric fields. Part of the shift between gas and solid phases is ascribed to zero‐point torsional oscillations of the molecule.