Transport phenomena in condensed systems, such as flow and diffusion, occur through the relaxation of molecuies which are under stress. The rate processes theory is applied to the relaxation process, and an equation for the rate of shear can be derived. Development of the shear formula is presented along with a developmental discussion of Newtonian and non-Newtonian flow. Also included in the discussion is distribution of flow velocities and molecular diffusion. (J.R.D.)