The goal of this paper is to show that a particular view of emotion sharing and a specific hypothesis on infant social perception strengthen each other. The view of emotion sharing is called “the straightforward view.” The hypothesis on infant social perception is called “the pairing account.” The straightforward view suggests that participants in emotion sharing undergo one and the same overarching emotion. The pairing account posits that infants perceive others’ embodied experiences as belonging to someone other than the self (...) through a process of assimilation to, and accommodation of, their own embodied experience. The connection between the two theories lies in the domain-general process of association by similarity, which functions both in the individuation of a unitary emotion and in the interpretation of the sensory stimulus. By elaborating on this connection, the straightforward view becomes more solid from the cognitive-developmental standpoint and the pairing account expands its explanatory power. Since the straightforward view requires minimal forms of self- and other-awareness, the paper provides a characterization of the developmental origin of the sense of us, i.e., the experience of self and other as co-subjects of a shared emotional state. (shrink)