The Institut Max von Laue-Paul Langevin (ILL) in Grenoble regularly orga nizes workshops that deal with various applications of neutrons in physics, chemistry, biology and materials science. The workshop "Quantum Aspects of Molecular Motions in Solids" was jointly organized by the Institut Laue Langevin and the Institut fiir Festkorperforschung at the Kernforschungsan lage Jiilich and took place in September 1986 in Grenoble. Tunneling phenomena in molecular crystals were first observed with macro scopic methods like specific heat experiments and later also with NMR. Fi nally, the development...