This book, the fourth in a series from the Materials Research Society, follows the tradition of earlier volumes in the series and covers a broad range of topics relating to structure and dynamics under geometric restrictions. Emphasis is on methods of probing confined systems, diffusion in porous media, polymers and membranes, dielectric and mechanical relaxation in nanopores, rheology and friction studies of embedded liquids, and properties of dendrimer supermolecules. Participants from many varied disciplines share their points of view on the fundamental questions of how spatial restrictions modify a system to behave significantly different than in bulk, how this difference relates to the molecular properties, and how it can be probed.