We review the phenomenological approach, on the macroscopic or Darcy scale, to flow and volume change in clays and other swelling media. The formulation represents the generalization to media subject to volume change of the well-established phenomenological approach to flow in non-swelling media primarily established in the context of soil physics. The one-dimensional generalization to swelling media is straightforward, and may be usefully applied to practical one-dimensional systems, including three-component systems with solid particles, water, and air. On the other hand, the further generalizations to two- and three-dimensional systems have not yet been developed fully convincingly. Difficult questions include the mode of stress transmission and the tensorial stress-strain relations in multidimensional and multi-component systems. One means of gaining insight into these questions for media of high colloid content (such as clays) is through relevant solutions of the Poisson-Boltzmann equation governing electrical double-layer interactions in dense arrays of colloidal particles. These solutions give pertinent information on both the macroscopic and the microscopic scales. We present a progress report on work along these lines.