Seven papers presented at a research conference on number and measurement are presented in this volume. The first paper provides an overview of research concerning number and measurement, and suggests directions for future research. The second paper discusses the relationships between measurement and number concepts, and psychological and instructional issues related to transfer. Two papers are devoted to synthesizing and analyzing research on measurement, and the delineation of questions about which research is needed. Two papers concern fractions; the first of these analyzes the foundations of the rational numbers from mathematical, cognitive, and instructional points of view, while the second reviews and synthesizes educational research related to fractions. The final paper concerns children's development of cardinal and ordinal number concepts. (SD)