In the title solvated compound, C28H19N2O4 center dot C2H6OS, the central beta-lactam ring is almost planar (r.m.s. deviation = 0.002 angstrom). It makes dihedral angles of 1.92 (11), 83.23 (12) and 74.90 (10)degrees with the methoxy-and chlorophenyl rings and the ring plane of the 1H-benzo[de]isoquinoline-1,3(2H)-dione group [maximum deviation = 0.089 (1)], respectively. An intramolecular C-H center dot center dot center dot O hydrogen bond closes an S(6) ring and helps to establish the near coplanarity of the beta-lactam and methoxybenzene rings. In the crystal, the components are linked by C-H center dot center dot center dot O hydrogen bonds, C-H center dot center dot center dot pi interactions and aromatic pi-pi stacking interactions [centroid-to-centroid distances = 3.6166 (10) and 3.7159 (10) angstrom], resulting in a three-dimensional network, The dimethyl sulfoxide solvent molecule is disordered over two sets of sites in a 0.847 (2):0.153 (2) ratio.