Performance measurement of large distributed multiagent systems (MAS) offers challenges that must be addressed explicitly in the agent infrastructure. Performance data is widely distributed and voluminous, and poor data collection can impact the operation of the system itself. However, performance metrics are essential to internal system function, e.g., autonomous adaptation to dynamic environments, as well as to external assessment. In this paper we describe the tools, techniques, and results of performance characterization of the Cougaar distributed agent architecture. These techniques include infrastructure instrumentation, pluginbased instrumentation of agents, and dynamic control of metric collection. We introduce multiple redundant “channels” for metric delivery, each serving separate quality of service requirements. We present our techniques for instrumenting the agent society, justify the metrics chosen, and describe the tools developed for collecting these metrics. We als...