Integrating and coordinating COTS software requires appropriate analysis and architectural design. Most integration architectures use message-oriented middleware for the interaction between COTS applications. However, the abstraction level of these one-to-one message exchanges is too low to aptly design the integration architecture's coordination aspects. The authors' approach, called BECO (business event-based coordination), improves organizational fit and flexibility by introducing an additional abstraction layer in the interaction stack. Business events are introduced as higher-level, many-to-many coordination units, which enforce consistent processing in multiple applications. Underneath, existing one-to-one communication technologies can be reused for event notification. Furthermore, business processes can be designed and enacted concisely as sequences of business events. The result is a consistent, flexible integration approach that can be layered entirely on top of existing technologies.