In spite of the rapid spread of agent technology, there is, as yet, little evidence of an engineering approach to the development of agent-based systems. In particular, development methods for these systems are relatively rare. One of the key reasons for this is the inadequacy of standard software development approaches for these new, and fundamentally different, agent-based systems. Traditional software development methods often lack the flexibility to handle high-level concepts such as an agent's dynamic control of its own behaviour, its ability to represent cooperative interactions, and its mechanisms for representing internal change, assumptions, objectives, and the uncertainty inherent in its interactions with the real-world.