Stigmergy has been variously adopted in MASs (multi-agent systems) and in other fields as well—as a technique for realising forms of emergent coordination in societies composed by a large amount of typically simple, ant-like, non-rational agents. In this article we introduce a conceptual and engineering framework for exploring the use of stigmergy in the context of societies composed by cognitive / rational agents, as a means for supporting high-level, knowledge-based social activities. We refer to this kind of stigmergy as cognitive stigmergy. Cognitive stigmergy is based on the use of suitable engineered artifacts as tools populating the agent working environment, and which agents share and rationally use for their individual goals. Artifacts are first-class entities representing the environment that mediates agent interaction and enables emergent coordination: as such, they encapsulate and enact the stigmergic mechanisms and the shared knowledge upon which emergent coordination processes are based.