At a first glance the reader of this book might be puzzled by the variety of its topics which range from phase-transition-like phenomena of chemical reactions, lasers and electrical currents to biological systems, like neuron networks and membranes, to population dynamics and socio logy. When looking more closely at the different subjects the reader will recognize, however, that this book deals with one main problem: the behaviour of systems which are composed of many elements of one or a few kinds. We are sure the reader will be surprised in the same way as the participants of a recent symposium on synergetics, who recognized that such systems have amazingly common features. Though the subsystems (e. g. electrons, cells, human beings) are quite different in nature, their joint action is governed by only a few principles which lead to strikingly similar phenomena. It hardly needs to be mentioned that once such common principles are established, they are of an enormous stimulus and help for future research. Though the articles of this book are based on invited papers given at the first International Symposium on Synergetics at Schlof. l. Elmau from April 30 to May 6, 1972, it differs from usual conference proceedings in a distinct way. The authors and subjects were chosen from the very beginning so that fmally a well organized total book arises. We hope that the reader will feel the same pleasure and enthusiasm the participants at the symposium had.