Role theory [6] deals with collaboration and coordination; roles have also been applied to distributed systems management [31] and to agent and robot systems [2, 43]. However, it has been difficult to realize these representations in an automated or semi-automated system, due to the lack of adequate formalism and corresponding abstractions in software. Role models are relatively new concepts in object-oriented software engineering that emphasize patterns of interaction and therefore rectify this situation for software analysis and design. This paper provides examples of agent role models and explains how role modeling can be used to facilitate agent system analysis and design. We also discuss role model implementations based on two approaches: the Role Object pattern and aspect-oriented programming (AOP).