Applications built in a strongly decoupled, eventbased interaction style have many commendable characteristics, including ease of dynamic configuration, accommodation of platform heterogeneity, and ease of distribution over a network. It is not always easy, however, to humanly grasp the dynamic behavior of such applications, since many threads are active and events are asynchronously (and profusely) transmitted. This paper presents a novel, complete approach that aids in the understanding, debugging, and visualization of the behaviors of event-based applications. It applies to real, implemented systems, without requiring the presence of component source code, and supports partial or incomplete, heuristic behavior specifications. A prototype implementation of our approach was applied to two systems, including the prototype itself, indicating that our approach is feasible, scalable, and shows promising results in terms of increasing the understandability of these types of systems.