The second Hans Freudenthal Medal of the International Commission on Mathematical Instruction (ICMI) is awarded to Professor Paul Cobb, whose work is a rare combination of theoretical developments, empirical research and practical applications. His work has had a major influence on the mathematics education community and beyond.

Born in a small town in southern England, Paul Cobb did not expect to develop an academic career. After earning a BSc with honours in mathematics from the University of Bristol, he spent a few years working as a secondary school mathematics teacher. In 1978 he enrolled into a one-year Masters programme in mathematics education at the University of Georgia in Athens. Little did he know at that time where this seemingly insignificant step would take him. A few years later he was already one of the rising stars of research in mathematics education. It did not take him much longer to gain an international recognition and become a central figure as well as a major influence in the field of mathematics education. He is now Professor at Vanderbilt University, in the US.

Paul Cobb's professional activity spans two decades and more than one research paradigm. Once a close collaborator of Ernst von Glasersfeld and of Leslie P. Steffe, he began his career as a developer, and subsequently a critic, of the theoretical perspective known as radical constructivism. Cobb's research and development projects, first in the field of elementary school mathematics and later of middle school statistics, are exemplary in many respects. They are a product of a comprehensive, well-designed, consistent, and constantly updated research programme. Its main strength is its sensitivity, both to the lessons learned from earlier implementations and to the evolving practical needs of the field of education.

The dynamic character of Paul Cobb's theoretical perspective is a natural outcome of his thoughtful studies. His work shows an acute awareness of the insufficiency of any over-delineated approach, and he has gradually moved the focus of his work from individual learners to teams, to classrooms, and to district-wide infrastructure. Across these settings, he has been systematically examining the consequences of the assumption that human learning is inherently social. In this respect, his work with Erna Yackel on sociomathematical norms paved important new ground. Thanks to this systematic foundational contribution, Paul Cobb is today regarded as one of the leading sociocultural theorists in the field of mathematics education and beyond, and his work is currently yielding new insights on issues such as equity and students' identities.

Paul Cobb is a prolific writer, widely read within the broad education community. His research spans more than a hundred journal articles and book chapters, as well as several books authored or edited with others. Prestigious journals, such as Educational Researcher, Cognition & Instruction, Journal of the Learning Sciences, Mind, Culture, and Activity have consistently published his work. Many of his publications have multiple authors, as do his numerous empirical studies. Paul Cobb's life project can thus be seen as a truly collective endeavour, implemented according to the same principles as those that he promotes in his educational writings.

Paul Cobb's work has had a tangible impact on the mathematics education vocabulary. It is through this work that such widely-used notions as taken-as-shared meaning or sociomathematical norms entered the professional discourse. The fact that his contribution is recognized and valued within the mathematics education community and beyond finds further confirmation in his numerous grants, distinctions and awards, and in particular, his recent election to the National Academy of Education of the US.