This volume contains papers which have been presented at the International Sym- posium on Metal Clusters in Heidelberg from April 7-11, 1986. Clusters, and in particular metal clusters, have been the topic of fa~t growing scientific interest. Indeed, clusters constitute a field of interdisciplinary nature where both physical and chemical questions have to be addressed. Clusters are offundamental importance for the deeper understanding of the transition from atoms via molecules and larger aggregates of particles to the properties of solid materials. Moreover, metal clusters and their character- istics are of vital significance for such applied topics as catalysis or photography. Experimentally, the field exhibited rapid progress in the last years. Different sources for clusters have been developed. Intense beams made possible the investigation of free neutral clusters and cluster ions as well. Even though a number of issues concerning metal clusters is still discussed controversially, the present volume tries to give an overview of current work in this field and to illustrate the large variety of experiments as well as the advances made possible by modern theoretical methods. Looking at the many interesting questions still to be addressed it is fair to propose a rapid further growth of this field.