This paper presents the idea that, across cultures, musical interaction is communicative and intrinsically affiliative, overlapping significantly in function with the phatic speech register. I will refer to experimental evidence that supports the view that joint music-making and phatic conversation can overlap not just in function but also in form. I will suggest that what can be interpreted as phatic conversation or as participatory music are manifestations of a superordinate domain of affiliative communicative interaction, and will submit that features that we tend to think of as musical —such as discrete patterns in pitch and rhythm— are best construed not as aesthetic properties but as interactive affordances that may be functional in the achievement of interpersonal affiliative alignment.