Stable unit dose detergent pacs are provided which are less prone to leakage or breakage and more aesthetically pleasing during handling. The unit dose pacs include a water-soluble container formed from a water-soluble or water-dispersible film and a wash composition encapsulated in the container. According to one embodiment, the wash composition includes an anionic surfactant present at from about 2% to about 35%, a non-ionic surfactant present at from about 2% to about 30%, and a solvent system present at from about 37.5% to about 80%, characterized in that the solvent system is composed of water and a single non-aqueous solvent only, or composed of water, a single non-aqueous solvent, and a residual solvent (less than 5%) only.