The present book is the outcome of an Advanced Study Institute meeting, which was held in Kallithea, Chalkidiki, in Northern Greece, from 12-25 May 1991 and attended by 69 delegates from 18 countries. The Institute brought together scientists, engineers and technologists currently involved in basic and applied research on the different aspects of flotation. The Institute covered subjects in four major areas of flotation: a) fundamentals; b) chemical technology aspects; c) mineral processing; and d) water and wastewater treatment. Apart from the papers reproduced in this volume, several short oral communications were also presented. Participants also had the opportunity to visit the Hellenic Chemical Products & Fertilizers Co. Ltd. mixed sulphides plant, in Chalkidiki. Conference participants, whose interest and research projects are in this broad field of science and engineering, provided a well-informed discussion of the problems encountered, as well as possible directions of future technological developments. It is hoped that this book is not only a good record of the presentations made (formal and informal), analyzing the state-of-the-art in flotation, but will also be helpful for students, scientists and technologists working in the fields of separation processes and in particular mineral processing and wastewater engineering. All the invited speakers and the participants made this summer school possible, worthwhile and enjoyable. The sponsorship by the NATO Scientific Affairs Division is gratefully ack­ nowledged. The Editors would like to thank the members of the Organizing Committee, Dr. B.A.