The goal of this chapter is to theoretically explore intersubjectivity when social development goes awry. More specifically, it will explore intersubjectivity and autism by combining work with infant intersubjectivity, anthropological dimensions of socialness, and sociocultural positions on mediated action and sense of self in order to conceptualize how social changes during adolescence might transfigure mutual engagement. A sociocultural framework that focuses on mediated action is outlined as one way that individual mental functioning and social phenomena come together. The idea that routines become cultural, symbolic tools and social others often function as animate tools that support late emerging intersubjectivity is developed within the paper. Case study material of one child with autism, as reported by the mother, is used to illustrate how intersubjectivity can be constructed by means of these tools after years of disruptive communication and social engagement.