Abstract. Agent interactions are frequently characterized as "coherent," "collaborative," "cooperative," "competitive," or "coordinated." These terms specialize the more foundational category of "correlation," which can be measured by the joint information of a system. "Congruence"is orthogonal to the others, reflecting the degree to which correlation and its specializations satisfy user requirements. A taxonomy of these mechanisms can guide the design of multi-agent interaction. Lack of correlation is sometimes necessary, and requires the use of formal stochasticity.