As suggested by the titles, the chapters in all three books deal with children's mathematical thinking and learning. The authors are leading psychologists and mathematics educators in this broad field of research, and the volumes present some of the most comprehensive, systematic, and careful research recently conducted on problems of current interest in the field. There is no question that these books will serve as major reference works for those interested in research on the learning of mathematics. With some exceptions, the volume edited by Lesh and Landau presents work of mathematics educators, and the volumes edited by Brainerd and by Ginsburg contain work of cognitive psychologists. The three volumes were selected for a single review because they represent significant approaches to studying a common problem—children's mathematical thinking and learning.