A new model for multiphase, multicomponent transport in capillary porous media is developed, in which the multiple phases are considered as constituents of a multiphase mixture. This multiphase mixture model consists only of the conservation equations for the multiphase mixture and is derived from the classic multiphase flow formulation without making any approximations. In addition, algebraic relations are found which can be used to back out the individual phase flow fields from the mixture velocity in a post-processing fashion. While being mathematically exactly equivalent to the traditional multiphase flow model, the present formulation significantly reduces the number of model equations, thus offering an efficient alternative for the theoretical analysis and numerical simulation of multiphase transport phenomena in porous media. A detailed application to two-phase, binary systems shows that the complex transport problems become more tractable within the framework of this new formulation.