In the Sociology of Emotion and Affect Studies, affects are usually regarded as an aspect of human beings alone, or of impersonal or collective atmospheres. However, feelings and emotions are only specific cases of affectivity that require subjective inner selves, while the concept of ‘atmospheres’ fails to explain the singularity of each individual case. This article develops a theory of social affect that does not reduce affect to either personal feelings or collective emotions. First, I use a Spinozist understanding of (...) the ‘body’ to conceptualize the receptivity and mutual constitution of bodies, to show how affects do not ‘belong’ to anybody; they are not solely attributable either to the human or to any kind of body alone, but emerge in situations of the encounter and interaction. Next I build upon Jean-Marie Guyau’s concept of transmissions to show how we can theorize affect as an emerging transmission between and among bodies. Finally, I demonstrate how we now have a complete conceptual frame for theorizing affect in relation to all bodies in any given social scene, the grand composition of which I call affectif. (shrink)