The use of atomic diffusion processes to understand the origin and evolution of the Earth and other Planetary systems are briefly reviewed in this paper. I outline some situations to illustrate how diffusion modeling may find varied applications in the Earth and Planetary Sciences. Some possible areas of research are described where advances in Geosciences may benefit researchers interested in diffusion processes in other fields. These include measurement of diffusion rates under high pressures, studies in multicomponent diffusion and modelling of diffusion and point defect related processes in multiphase and multicomponent non-metallic systems. Finally, I outline some areas where input from specialists in other areas may advance knowledge in the Geosciences.