The first three chapters in this section are related in interesting ways, which we hope to bring out in this critique. We feel that von Glasersfeld's (chap. 20) radical constructivism opens up a space for Wood, Cobb, and Yackel (chap. 22) and Driver (chap. 21) to bring sociocultural aspects into the account of the individual's construction of knowledge. We indicate that "opening," and then we turn to the differences in the way the latter two chapters use that opening. To help the reader understand our bias, we state at the outset that, in our own work, we have been influenced by the ideas of both Piaget and Vygotsky.