Models, Architecture, and Design -- A Reference Architecture for Situated Multiagent Systems -- A Unified Model for Physical and Social Environments -- Exploiting the Environment for Coordinating Agent Intentions -- CArtA gO: A Framework for Prototyping Artifact-Based Environments in MAS -- Mediated Interaction and Stigmery -- Environment as Active Support of Interaction -- Environmental Support for Tag Interactions -- Cognitive Stigmergy: Towards a Framework Based on Agents and Artifacts -- Trace Signals: The Meanings of Stigmergy -- Regulation Function of the Environment in Agent-Based Simulation -- Governing Environment -- Establishing Global Properties of Multi-Agent Systems Via Local Laws -- E4MAS Through Electronic Institutions -- Spatially Distributed Normative Infrastructure -- Enhancing the Environment with a Law-Governed Service for Monitoring and Enforcing Behavior in Open Multi-Agent Systems -- Applications -- Urban Traffic Control with Co-Fields -- Designing Self-organising MAS Environments: The Collective Sort Case.