This paper presents a metamodel formalizing collaboration of heterogeneous entities (organizations, agencies, companies, intelligent agents…). Initially developed to support crisis management, this metamodel has been extended to any objective driven work of collaborative networks (CN). This formalism embeds all concepts (and inter-relations between them) required to represent any collaborative situation aiming at meeting some CN’s objectives using sets of capabilities provided by each involved stakeholder. This metamodel is the keystone of a model driven decision support system (under development) designing collaborative processes that can optimize the coordination of collaborative stakeholders. The metamodel expressiveness is briefly illustrated through a use-case.