A central assumption in joint action research is that in order to explain how individuals act as part of a group, we must first explain how the group comes into existence. This assumption has led to an unnecessarily narrow research programme: research has focussed largely on interpersonal coordination mechanisms. I outline an alternative approach predicated on a dynamic conception of the ecosystem. On this view, there is no need to assume that actors must first constitute a group agent with their fellows before entering into coordinated action. Such coordination can be more efficiently explained by recognizing that all actions perturb the structure of the ecosystem itself in a manner that can alter the action possibilities available to neighbouring actors. This move allows us to overcome entrenched debates over the nature of shared intentionality, and to instead focus on practical interventions in multi-actor settings.