This paper describes how to refine a Gaia design by applying agent-oriented extensions of UML. First, we show how the Gaia Interaction model can be improved by applying the first two layers of the Agent Interaction Protocol (AIP) of AUML. Second, Gaia Agent and Service models are refined by applying the AIP’s third layer combined with Extended UML Class Diagrams. Third, Gaia Organisational Structure is enriched by applying the Aalaadin model. The final aim of the whole process is to obtain a more concrete design closer to implementation. We demonstrate how the refinement process can be applied to the development of an agent-based system for conference management.