A combined theoretical, computational and experimental study of binary and ternary supermolecular spectra of simple, dense gases is described. We consider interaction-induced dipoles of nonpolar gases and their associated, collision-indued absorption spectra, and interaction-induced polarizabilities of both, Raman-inactive and -active atoms and molecules and their associated, collision-induced Raman spectra. For the binary supermolecular systems, quantum line shapes and spectral moments are computed from first principles and compared with measurements; close agreement is generally found. Ternary systems, on the other hand, are treated in terms of virial expansions of line shape and spectral moments. Spectral moments of the pairwise additive, 3-body, induced dipole and polarizability components have been computed, based on reliable input, and are compared with measurement. For most ternary cases considered, close agreement between calculation and measurement was not observed, presumably because of the presence of an irreducible 3-body component which is not of the classical, long-range type. Rather, it arises from electron exchange by near-range interactions.