The stability of stratified three phase flow (water-oil-gas) was analyzed using two approaches : A straight forward Kelvin-Helmholtz stability analysis on the two interfaces termed here the "exact" approach and a simplified approach. In the "exact" approach the two interfaces (water-oil and oil-gas) are perturbed, while in the simplified approach the perturbed interface is only the upper oil-gas interface. Both approaches include the viscous Kelvin-Helmholtz analysis in which the shear stresses are taken into account and the inviscid KH analysis where the shear stresses are neglected. Comparison with some experimental results suggests that the simplified method is a better predictor of the transition from stratified flow than the "exact" approach, suggesting, perhaps, that the stability analysis on the upper interface alone is preferred.