This book deals with the evolution of the properties of clusters, nanostructures and cluster-based materials, with emphasis on the role of the interface. These materials are characterized by reduced size, dimension and symmetry, and possess many novel properties that are not commonly seen in their bulk phases. The topics include synthesis, nucleation, growth, characterization, atomic and electronic structure, dynamics, ultra-fast spectroscopy, stability; electrical, magnetic, optical, thermodynamic and catalytic properties of clusters (free and supported); cluster materials (self-assembled, ligated and embedded); nanostructures (quantum dots, wells and corrals; nanotubes and wires; colloidal and biological materials) and nano-technology (electronic, magnetic and optical devices). In addition to presenting the current status of the field, the book discusses outstanding problems and future directions.