Atomic clusters and nanoparticles. Agregats atomiques et nanoparticules : Les Houches Session LXXIII 2 28 July 2000 This book focusses on basic science but it also addresses engineers interested in new materials. Experiments on metal clusters are reviewed in two long pedagogically written articles. The theoretical courses covered three main domains: (1) electronic properties of metallic clusters and nanostructures (2) phases and phase changes of small systems and (3) chemical processes in nanoscale systems. Furthermore the interested readers researchers as well as graduate students will find articles on density functional theory magnetic properties of clusters and computer simulations of cluster dynamics. In addition the book addresses chemical processes pairing correlation effects and also biological systems