The Computation of van der Waals Interactions Ian Snook RMIT, Department of Applied Physics, GPO Box 2476V, Melbourne, Victoria, Australia, 3001 Dispersion or van der Waals forces (potentials) play a key role in many phenomena e.g. "docking" of biological molecules, in colloidal and nano-crystal stability, the phase behaviour of non-polar substances, and in most areas of soft condensed matter. How ever, the calculation of such interaction potentials from first principles is difficult for atoms and extremely difficult for systems involving surfaces. This talk will outline the basic ideas behind these calculations and their importance. In particular the problems involved in applying the two most popular methods i.e. Symmetry Adapted Perturbation Theory and Supermolecule methods to even the simplest systems will be outlined. Some ideas for the future will also be discussed.