In this paper, we show that early interaction can be seen as comprising of strands of coordinated activity on multiple levels and timescales. In tracing the development of such multilayered organization from an embodied and situated perspective, we underscore the role of the reliable presence of the structured environment, an enacted niche, supporting the segregation and integration of participatory interaction strands. This perspective allows us to study the development of social coordination not only in terms of development of individual skills but, crucially, as a change of participatory emergent patterns, a transformation in engagement. We illustrate this approach with some results from the collaborative research project on Early Semantic Development (EASE). Using qualitative microanalysis combined with quantitative dynamical time series analyses, we were able to demonstrate several layers of such organization: from local forms of coordination, such as basic informational coupling within a modality, and the emergence of specific social affordances, to more global co-action structures such as affect imbued ‘action arcs’ – dynamic action contours with a beginning, build-up, climax and resolution, co-enacted by participants. Pointing to future work, we underscore the potential of these global structures to contribute to the emergence of more complex interactions, such as composite activities within ‘pragmatic frames’, narratives, or language.