Gaia was the first complete methodology proposed for the development of multi-agent systems (MASs), and was subsequently improved to designing and building systems in complex, open environments. Gaia focuses on the use of the organizational abstractions to drive the analysis and design of MAS. Gaia models both the macro (social) aspects and the micro (agent internals) aspects of MAS, and devotes a specific effort to model the organizational structure and the organizational rules that govern the global behavior of the agents in the organization. In this chapter we present the complete documentation of the Gaia process following the IEEE-FIPA Documentation Template.