Improvising musicians—especially towards the “freer” or more “experimental” end of the spectrum—are often seen as having the space to do just about anything. But actual improvisations are (also) processes of what enactivist philosophers Hanne De Jaegher and Ezequiel Di Paolo call “participatory sense-making”; musicians’ active choices are both enabled and constrained by musical phenomena, or “autonomous organising principles”, that emerge between them. Here we explore one example of such phenomena: groove. We begin by theorizing groove more broadly as a “grid” and as “participatory discrepancies”, emphasizing how groove shows a form of agency in processes of sense-making. We then analyze sense-making at work in a case of emergent groove performed by the 21-piece experimental improvising ensemble Splitter Orchester. We conclude that collective sense-making is a dynamic process in which individual agents negotiate not only with each other, but also the shared norms and emergent other-than-human processes that they enact.