Tunable synchrotron radiation has been used to probe the dissociation dynamics of ethylene sulfide, providing selective determination of the translational energy distributions of both excited (D-1) and ground-state (P-3) sulfur atoms, with momentum-matching to the ethylene cofragments. The results suggest the presence of a channel giving S(P-3) in conjunction with triplet ethylene C2H4 (B-3(1u)), and allow for the first experimental measure of the energy of the latter species near the equilibrium geometry, in which the two methylene groups occupy perpendicular planes.