<em>Stigmergy</em> has been variously adopted in MASs (multi-agent systems) and in other fields as well&mdash;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 <em>cognitive stigmergy</em>.
Cognitive stigmergy is based on the use of suitable engineered <em>artifacts</em> as tools populating the agent working environment, and which  agents share and rationally use for their individual goals.
In this seminal paper, we introduce an agent-based framework for cognitive stigmergy based on artifacts.
After discussing the main conceptual issues&mdash;the notion of cognitive stigmergy, the role of artifacts&mdash;, we sketch an abstract architecture for cognitive stigmergy, and we consider its implementation on the TuCSoN agent coordination infrastructure.