This volume on Clusters brings together contributions from a large number of specialists. A central element for all contributions is the use of advanced computational methodologies and their application to various aspects of structure, reactivity and properties of clusters. The size of clusters varies from a few atoms to nanoparticles. Special emphasis is given to bringing forth new insights on the structure and properties of these systems with an eye towards potential applications in Materials Science. Overal, the volume presents to the readers an amazing wealth of new results. Particular subjects include water clusters, Silicon, Iron, Nickel and Gold clusters, carbon-titanium microclusters and nanoparticles, fullerenes, carbon nanotubes, chiral carbon nanotubes, boron nanoclusters and more.