In this paper, we describe the latest version of SIBYLLE, an AAC system that permits persons suffering from severe physical disabilities to enter text with any computer application and also to compose messages to be read out by a speech synthesis module. The system consists of a virtual keyboard comprising a set of keypads which allow entering characters or full words by a single-switch selection process. It also comprises a sophisticated word prediction component which dynamically calculates the most appropriate words for a given context. This component is auto-adaptive, i.e. it learns on every text the user has entered. It thus adapts its predictions to the user's language and the current topic of communication as well. So far the system works for French, German and English. Earlier versions of SIBYLLE have been used since 2001 in the Kerpape rehabilitation center (Brittany, France).