This chapter provides an analysis of present theories and conceptualizations of intersubjectivity as well as psychological processes that have conceptual overlaps with intersubjectivity. The analysis shows how what counts as “intersubjective” behavior reflects the assumptions and analytic frames of each theorization and disciplinary focus. For example, psycholinguistic and sociolinguistic approaches define intersubjectivity as tied to language, whereas psychodynamic and cognitive science theories define intersubjectivity as primarily affective or embodied. A cultural critique is bolstered by findings from both cross-culture and within-culture studies of children’s interactions with adults and peers that show the predominance of nonverbal modes of interaction, such as mutual observation. These findings support a theory of intersubjectivity that allows for multiple forms and dimensions of interactive behavior, considers the cultural and historical context of the interaction, and recognizes how tools and tasks mediate shared activity