S.P. Bates and R.A. van Santen, The Molecular Basis of Zeolite Catalysis: A Review of Theoretical Simulations. J.F. Haw and T. Xu, NMR Studies of Solid Acidity. N. Sheppard and C. De La Cruz, The Vibrational Spectra of Hydrocarbons Adsorbed on Metals Part II--Adsorbed Acyclic Alkynes, Alkanes, and Cyclic Hydrocarbons Including Aromatics; Surface Hydrocarbon Groups Derived from the Decomposition of Alkyl Halides, etc. C.S. Clausen, H. Topsoe, and R. Frahm, Application of Combined X-ray Diffraction and Adsorption Techniques for In situ Catalyst Characterization. D.D. Whitehurst, T. Isoda, and I. Mochida, Present State of the Art and Future Challenges in the Hydrodesulfurization of PolyaromaticSulfur Compounds. B. Driben-Holscher, Multiphase Homogeneous Catalysis. Subject Index.