A number of developments over the last two decades or so make it timely for Body & Society to host a Special Issue on the theme of affect. A number of concepts have appeared in the social and human sciences, as well as in the natural sciences, that emphasize the fact that social and natural phenomena are complex, processual, indeterminate, relational and constantly open to effects from contiguous processes.Additionally, interest in the theme of 'affective labour' and the capitalization or economization of affect and emotion through teletechnologies and a multitude of therapies have drawn attention to affect as a phenomenon in need of fresh study. 1 Advances in the fields of genetics and biological sciences, mathematics, quantum physics/the physics of small particles, neurosciences, narrative analysis, media and information theory have contributed to this epistemological shift. In its wake, a common ontology linking the social and the natural, the mind and body, the cognitive and affective is beginning to appear, grounded in such concepts as assemblage, flow, turbulence, emergence, becoming, compossibility, relationality, the machinic, the inventive, the event, the virtual, temporality, autopoiesis, heterogeneity and the informational, for example. One important focus of this Special Issue is to spark interest and ongoing engagement in questions of method and experimentation in light of the common ontologies emerging across the humanities, and the natural, social and human sciences.