Probable molecular structures of diglyme in the solid state are deduced from a combination of ab initio calculations and inelastic neutron scattering vibrational spectroscopy. The final molecular structures closely resemble that of lithium diglyme, suggesting that all-trans segments are of minor importance in the solid phase. The molecular structures of pure diglyme closely resemble those of lithium ion coordinated diglyme and suggest that no large conformational changes are necessary for lithium ion complexation, The general strategy for obtaining structural information from vibrational spectra is discussed.