The past 13 years of activities of the International Group for the Psychology of Mathematics Education (PME) have provided researchers in mathematics education with a wide range of valuable interactions. The fruitfulness of these interactions is partly due to the variety of these researchers' backgrounds, which has permitted confrontations and collaborations among psychologists, mathematicians, and mathematics educators; it is also due in part to the exchanges at an international level that have facilitated discussions of different research perspectives, as is clearly exemplified in several sections of this book. In particular, the willingness of PME to encourage and support the existence of working groups and discussion groups alongside traditional research reports during its annual meetings has played an especially crucial role in creating a dynamic movement leading to new perspectives in this field of research.

New fields of research, such as research on learning processes in a microcomputer environment and on the learning of mathematics at an advanced level of education have emerged. But more important is the fact that beyond the initial psychological problématique, the debates about the presented research made clear the need to take new aspects into account.