In porous media, there are a variety of configurations in which three immiscible fluids can be distributed within a single body. For example, the fluids may be distributed as concentric rings. Alternatively, two fluids may be dispersed as separate blobs within the third fluid. The configuration governs the mobility of each fluid, and under equilibrium conditions is dictated by the three phase capillary pressure of the system. If the capillary pressure is altered, the configuration will change. Capillary pressure can be altered by flow of any phase through the pore body. However, in a three phase system flow cannot be described as simply "drainage" or "imbibition." Rather, flow must be described as "drainage/drainage," "drainage/imbibition" or "imbibition/imbibition" to account for the change in saturation of all three phases. This paper elaborates on the issues governing three phase capillary pressures and presents some first experimental results on oil/water/gas capillary pressures in a drainage/drainage mode.