The Second Winter School on the " hysics of Finely Divided Matter" was held at the Centre de Physique des Houches from 25 March to 5 April 1985. This meeting brought together experts from the areas of gels and porous media. People with different backgrounds - chemists, physicists - from university as well as industrial labora tories, had the opportunity to compare their most recent experimental and theoreti cal results. Although the experimental situations and techniques may seem at first sight unrelated, the theoretical interpretations are very similar and may be divided roughly into two...