Macroemulsions are inherently thermodynamically unstable systems which exhibit lifetimes which depend on the initial state of the system and the rates of creaming and coalescence. A previous study has shown an apparent relationship of emulsion stability to the thermodynamic equilibrium) phase behavior of systems containing surfactant/hydrocarbon/water M. Bourrel, A. Graciaa, R. S. Schechter, and W. H. Wade, J. Colloid Interface Sci. 72, 161 (1979)) . It was found that macroemulsions are most stable at the boundaries which separate two phase systems from those which form three phases consisting of a microemulsion in equilibrium with excess hydrocarbon and water phases. The present investigation shows that on approaching the three-phase boundaries those factors, such as the density difference between phases, the continuous phase bulk viscosity, and the surface viscosity, which tend to influence the rate of creaming, all act to decrease it. Hence at the phase boundary creaming is shown to be a slow step, thereby causing the emulsion to appear to be stable. It was also found that, despite the fact that the surface viscosity is maximum at the boundaries, coalescence becomes more rapid as the boundaries are approached. Thus, while the time scale for creaming increases, that for coalescence decreases. Overall, then, macroemulsions formed well away from the phase boundaries cream first, but persist longest. Within the three-phase region where the surfactant system is balanced equal concentrations of surfactant in the excess phases) coalescence proceeds at a remarkable, but unexplained, speed. In this region macroemulsions coalesce before they cream and emulsion stability is least. These observations are shown to apply to systems in the presence of varying quantities of alcohol. The phase behavior was adjusted by varying the electrolyte concentrations.