In the present paper the recent developments in condensation theories and models for binary droplet growth or evaporation are reviewed. The applicability of different theories ranging from exact models to analytical solutions is discussed. As an overall result it can be stated that for slow condensation (or evaporation) even simple linearized approaches yield satisfactory approximations. However, in the cases of rapid condensation and strong coupling of fluxes, only exact nonlinear expressions accounting for coupled mass and heat fluxes are applicable.