This paper discusses the distinct meanings of "internalization" and "interiorization" as ways of rendering intelligible the social constitution of the psychological in a line of research that started with Piaget and extended into a post-Piagetian reformulation of intelligence in successive generations of studies of the relations between social interaction and cognitive development. While the same clarity cannot be found in Vygotsky's work, the emphasis on the cultural embeddedness of cognitive activity in contemporary cultural psychology has also been a significant influence on the evolution of this work. This paper proposes a further integration of these perspectives by developing the idea of "operativity-in-context" as a means of retaining the advantages of Piaget's structural analysis of cognition whilst recognizing the situational and cultural constraints on cognitive functioning.