Geoffrey Saxe has conducted research on mathematical cognition in a variety of settings, including remote parts of Papua New Guinea, urban and rural areas of Northeastern Brazil, family practices involving numerical activities in the lives of toddlers, and elementary and middle school classrooms in the United States. He has been awarded grants from the National Science Foundation, the Spencer Foundation, and the Institute of Education Sciences. Other awards include a fellowship at the Center for Advanced Study in the Behavioral Sciences, a Fulbright Fellowship, Rockefeller’s Bellagio Center, a Presidential Citation from the American Educational Research Association. His books include Culture and Cognitive Development: Studies in Mathematical Understanding (1991),Cultural Development of Mathematical Ideas (in press), a monograph, Social Processes in Early Number Development (with S. Guberman and M. Gearhart, 1987). He has served on standing grant proposal review panels for the National Science Foundation, the Spencer Foundation, and the National Academy of Education. He is past Editor of the journal, Human Development, and a continuing member of the editorial boards of the Journal of Cognitive Development, Journal of the Learning Sciences, Cognition and Instruction, and the Journal of Applied Developmental Psychology. He recently completed a 3-year term as President of the Jean Piaget Society and is a standing member of the National Academy of Education. His current design research project with graduate students and faculty, Learning Mathematics through Representations, focuses on building on student thinking to support rich and generative knowledge about integers and fractions.