Machine translation services available on theWeb are getting increasingly popular. Multiple translation services are often combined for intercultural communication. Furthermore, since English is most frequently used as a hub language, it is often necessary to cascade different translation services to realize translations between non-English languages. As a result, the word sense is often changed because of the inconsistency, asymmetry, and intransitivity of word selections between machine translation services. Therefore, we propose a context-based coordination framework in which the context is propagated among cascaded translation services by referring to multilingual equivalent terms. By considering machine translation services as black boxes, we achieve substantial quality improvements through Web service coordination.