At the annual meeting of the Executive Committee of the International Union of Psychological Science (IUPsyS) in Stockholm in 1997, we considered various ways to commemorate the 50th anniversary of IUPsyS, which is to be celebrated at the occasion of the 27th International Congress of Psychology in Stockholm in July 2000. At that time, the archives of IUPsyS were being transferred from Leuven (Belgium) to Montréal (Canada); while packing, we realized how rich the history of IUPsyS is. Admittedly, going through the minutes of the Executive Committee and Assembly meetings over the almost 50 years of its existence is a rather boring exercise; still, they do contain immensely valuable information from the past and important lessons to be drawn for future activities of IUPsyS. The critical problem was to find colleagues willing to process the available information and to transform it into a text which could be both read enjoyably as the history of IUPsyS and also contain sufficient detail for archival purposes. The idea emerged to invite a few Honorary Life Members of the IUPsyS Executive Committee as authors. It was a nice way to get them involved once again in the activities of IUPsyS; also, we could profit from their extended past experience with the Union. We contacted Mark R. Rosenzweig and Wayne Holtzman (both Past-Presidents), and David Bélanger (past Treasurer); they all immediately accepted the invitation. Michel Sabourin (current Treasurer) joined the authors. We do realize how much time and work were involved in order to get the book ready for the Stockholm congress. On behalf of the whole IUPsyS Executive Committee, I wholeheartedly thank them. I also wish to convey our thanks to Psychology Press, who were willing to publish a book appealing mainly to readers interested in international psychology and in the history of psychology.

Leuven, February 29, 2000
Géry van Outryve d’Ydewalle
IUPsyS President