The first volume of the proceedings of the 21st annual meeting of the International Group for the Psychology of Mathematics Education contains the following 13 full papers: (1) "Some Psychological Issues in the Assessment of Mathematical Performance" (O. Bjorkqvist); (2) "Neuromagnetic Approach in Cognitive Neuroscience" (S. Levanen); (3) "Dilemmas in the Professional Education of Mathematics Teachers" (J. Mousley and P. Sullivan); (4) "Open Toolsets: New Ends and New Means in Learning Mathematics and Science with Computers" (A. A. diSessa); (5) "From Intuition to Inhibition--Mathematics, Education and Other Endangered Species" (S. Vinner); (6) "Distributed Cognition, Technology and Change: Themes for the Plenary Panel" (K. Crawford); (7) "Roles for Teachers, and Computers" (J. Ainley); (8) "Some Questions on Mathematical Learning Environments" (N. Balacheff); (9) "Deepening the Impact of Technology Beyond Assistance with Traditional Formalisms in Order To Democratize Access To Ideas Underlying Calculus" (J. J. Kaput and J. Roschelle); (10) "The Nature of the Object as an Integral Component of Numerical Processes" (E. Gray, D. Pitta, and D. Tall); (11) "Unifying Cognitive and Sociocultural Aspects in Research on Learning the Function Concept" (R. Hershkowitz and B. B. Schwarz); (12) "Emergence of New Schemes for Solving Algebra Word Problems: The Impact of Technology and the Function Approach" (M. Yerushalmy); (13) "Approaching Geometry Theorems in Contexts: From History and Epistemology To Cognition" (M. A. Mariotti, M. G. Bartolini Bussi, P. Boero, F. Ferri, and R. Garuti). In addition, volume 1 contains three brief reaction papers (two reacting to Gray and one to Mariotti), and 92 one-page abstracts of working group sessions, discussion group sessions, short oral communication sessions, and poster sessions. (ASK)