This article presents Gaia: a methodology for agent-oriented analysis and d
esign. The Gaia methodology is both general, in that it is applicable to a
wide range of multi-agent systems, and comprehensive, in that it deals with
both the macro-level (societal) and the micro-level (agent) aspects of sys
tems. Gaia is founded on the view of a multi-agent system as a computationa
l organisation consisting of various interacting roles. We illustrate Gaia
through a case study tan agent-based business process management system).