For aqueous solutions containing vesicles formed by sodium di-n-dodecyl phosphate, the gel to liquid-crystal transition occurs near 35 degrees C, the temperature T-m. When ethanol is added, T-m decreases, but the scan shows evidence of several transitions as more alcohol is added. The effect of added THF and propanol is similar but more dramatic. The scans are similarly complicated if the aqueous solutions are prepared using a solution of DDP in ethanol. However, vesicle <-> ethanol interactions are endothermic although the shift in T-m points to direct binding of alcohol into the vesicle.