Thermodynamic reasoning is a central aspect of our understanding of su
rfactant self-assembly. It provides both a conceptual framework and a
basis for a quantitative interpretation of experimental results. Recen
t theoretical advances have been made in the understanding of size and
shape of the micellar aggregates and the forces that lead to their fo
rmation, the theory describing the equilibrium between micelles and ve
sicles, the thermodynamics of microemulsion formation, and the modelli
ng of solubilization of apolar solutes into aqueous systems of micelle
s/vesicles.