Emulsion liquid-membrane systems can provide effective systems for removal of impurities in a variety of applications. In these systems, removal efficiency and the ability to concentrate impurities can be impaired because of encapsulated-phase leakage and emulsion swell. This work describes the results of a factorial experimental procedure that measured the effects of several formulation and operating variables on emulsion liquid-membrane leakage and swell. The experimental variables studied were surfactant concentration, osmotic pressure, membrane type, internal-phase volume fraction, and extraction-vessel stir rate. Encapsulated-phase leakage is influenced by all of the variables in a complex fashion. Emulsion swell results are consistent with a simple water-transport mechanism.