In this essay we suggest that Vygotsky's concept of the social provide the missing meaning for the concept of the social in the theory of situated learning by Lave and Wenger. According to Park, Vygotsky expanded the concept of the social so that it means not only interactions among people but also whatever socio-cultural-historical factors that constitute the patterns of the interactions. However, Park's claim of Vygotsky's expanding the concept lacks textual evidence. Vygotsky uses the term "social" to refer to the fact that both human and child development have a unique feature that is absent in animal development. The unique feature is that the basis of the development is the function of collaboration, or command, as a way of controlling behavior as well as mental functions. The function of collaboration initially manifest in the form of activity in which others command the child and then in the form of mental operation by the child. Behind such uses of the term "social" lies Vygotsky's concept of the social, namely that human and animal are qualitatively different; the basis of child development from the beginning to the end is the function of collaboration; man is social being in the sense that one can be free and independent by controlling her mental functions in the way she was controlled by others.