A three-component phase diagram of a system containing water, dimethyl isosorbide and Laureth 4 (Brij® 30), a commercial surfactant, was determined, and the kinetics of vesicle formation from dilution with water of the hydrotrope solution was studied using a stop-flow process in conjunction with light-scattering determinations. The phase diagram consisted of a large microemulsion phase and a lamellar liquid crystalline region. Results from the stop-flow/light-scattering determinations were tentatively interpreted using the Aniansson-Kahlweit-Zana theory of micellar relaxation for a system close to equilibrium. The interpretation indicated the vesicles to be formed by monomolecular buildup for surfactant concentrations less than 5%, while for vesicles formed at greater concentrations an agglomeration of vesicle fractions appeared more reasonable.