CArtAgO is a platform and infrastructure providing a general-purpose programming model for building shared computational worlds — referred here as work environments — that agents, possibly belonging to heterogeneous agent platforms, can exploit to work together inside a Multi-Agent System. Being based on the A&A (Agents and Artifacts) conceptual model, CArtAgO work environments are modelled and engineered in terms of set of artifacts programmed by MAS designers, collected in workspaces. From the agent viewpoint, artifacts are first-class entities representing resources and tools that agents can dynamically instantiate, share and use to support their individual and collective activities. After describing the basic motivations behind the approach, the chapter provides an overview of the programming model promoted by CArtAgO for the definition of artifacts (MAS designer's viewpoint) and for the use of artifacts (agent's viewpoint), using Jason as reference platform for MAS programming.