This book dealing with stance and motion was planned in June 1986 at a meeting held in Moscow and Leningrad between a group of Soviet and French scientists interested in motor control. This meeting took place in the framework of an exchange program between the USSR Academy of Seiences and the French Centre National de la Recherche Scientifique. It was very successful event and was greatly appreciated by all those who attended it. Several participants put forward the proposal that the possibility of publishing a book was worth exploring. What were the reasons for publishing a book on stance and motion— The interest aroused in the participants by each others contributions was not a sufficiently decisive argument. It was feit, however, that a large proportion of the orginal material presented at the meeting, especially in the field of posture and locomotion but also on other aspects covered by the book could be presented in a summarized form which should appeal to a larger audience because the facts and hypotheses they contained especially those from the Soviet participants, were not very familiar among international circles, and that many scientists would appreciate having a single volume containing a survey of the current state of research in this field. This was also the opinion of Plenum Press, who agreed to publish the book. Each participant at the meeting submitted a paper which was examined by two referees before being accepted.