The effect of dimethyl ether solvation on aggregated forms of the lithium enolate of acetaldehyde (CH2=CHOLi)(n)(Me2O)(x), n = 1-4, x = 0-4, was studied theoretically. Density functional theory (DFT) with the B3LYP functional was applied to calculate the energies of PM3 optimized structures (B3LYP//PM3). The accuracy of this method was checked successfully against a representative set of B3LYP//B3LYP computations. The DFT values also were calibrated by comparison with MP4 calculations on solvated methyllithium. The structures and energies of the aggregates are described, with emphasis on the main factors that control relative stabilities. Common crystal structure motivs are reproduced. Solvation is critical in the equilibria among the aggregated species and in the relative stabilities of the tetrameric isomers but is balanced by pi-interactions between lithium and the enolate double bond. A number of tetramer structures were studied, but lithium is tetracoordinated only in the cubic tetramer in the most stable solvated form. Aggregation and successive solvation energies as well as entropy considerations indicate that solution equilibria are dominated by the solvated monomer and tetramer. The disolvated monomer is remarkably stable; addition of a third solvent is far less exothermic than the first two additions and may not suffice to compensate for the corresponding entropy change. Natural population analysis (NPA) suggests that polarization rather than delocalization of charge from oxygen into the enolate double bond is the main mechanism of charge distribution. Previously known experimental aggregation data on lithium enolates are rationalized by the computational results obtained.