A lucid account of the fundamental physics of all types of microclusters, outlining the dynamics and static properties of this new phase of matter between a solid and a molecule. Since the book's first publication, the field of microclusters has experienced surprising developments, which are reviewed in this new edition: The determination of atomic structure, spontaneous alloying, super-shell, fission, fragmentation, evaporation, magnetism, fullerenes, nanotubes, atomic structure of large silicon clusters, superfluidity of a He cluster, water clusters in liquid, electron correlation and optimizsation of the geometry, and scattering.