This paper looks at enterprise interoperability (EI), specifically process-level interoperability, and suggests that the inherent non-determinacy of human-centred business processes introduces another ingredient into the EI puzzle that has thus far been understated in EIF ontologies. A conceptualisation of business process based on socio-technical concepts is presented. It is argued that this provides a better way to accommodate human agency factors, and under the influence of these factors, how business processes inevitably evolve over time, potentially affecting their interoperability. We suggest the extant body of knowledge on the theory of dynamic capabilities is relevant to understanding how organisations can control this potentially undirected process evolution and thereby sustain interoperability. Some initial observations are made concerning how this new ontological element could be accommodated into existing EIFs. The paper aims to stimulate discussion in this area and make a contribution to the EI body of knowledge.