Dispersants used in the mitigation of oil spills are mixtures of amphiphilic molecules (surfactants) dissolved in a solvent. The recent large-scale use of dispersants has raised environmental concerns regarding the safety of these materials. In response to these concerns, our lab has developed a class of eco-friendly dispersants based on mixtures of the food-grade surfactants soy lecithin (L) and Tween 80 (T) in a solvent. We have shown that these “LT dispersants” are very efficient at dispersing crude oil into seawater. The solvent for dispersants is usually selected based on factors like toxicity, volatility or viscosity of the overall mixture. But with regard to dispersion efficiency of crude oil, the solvent is considered to play a negligible role. In this thesis, we re-examine the role of solvent and show that it can actually have a significant impact on the dispersion efficiency. That is, the dispersion efficiency can be altered from good to poor simply by varying the solvent while keeping the same amounts of surfactants. We devise a systematic procedure for selecting the optimal solvent by utilizing Hansen Solubility Parameters (HSPs). Our analysis enables us to identify solvents that combine high dispersion efficiency, good solubility of the LT surfactants, a low toxicity profile, and a high flash point.