This document is divided into two major sections. The first part consists of approximately 60 papers which were presented at the fifth conference of the International Group on the Psychology of Mathematics Education, which was held in Grenoble, France, in July 1981. The papers are categorized into the following major themes: (1) number construction, addition and subtraction, decimals, and geometry in the primary school; (2) proportion and product, algebra, function, and rational numbers in secondary school; (3) problem solution and memory, stages and categories of mathematical thought, logic and representation, and methodological problems; and (4) university teaching, attitude and anxiety, bilingualism, and teacher training. The second part consists primarily of the texts of four plenary lectures which served to outline the main international research orientations. Appended are several papers which missed initial inclusion in the first portion of the document. (MP)