Abstract--The development of large-scale distributed multiagent systems in open dynamic environments is a challenge. System behavior is often not predictable and can only be evaluated by execution. This paper proposes a framework to support design and development of such systems: a framework in which both simulation and emulation play an important role. A distributed agent platform (AgentScape) is used to illustrate the potential of the framework. Keywords-multi-agent systems, agent-based simulation, emulation, development, distributed systems