The problems involved in the development of user interfaces become even more severe through the ubiquitous use of a variety of devices such as PCs, mobile phones and PDAs. Each of these devices has its own specifics that require a special user interface. Therefore, we developed and implemented an approach to generate user interfaces for multiple devices fully automatically from a high-level model. In contrast to previous approaches focusing on abstracting the user interface per se, we make use of speech act theory from the philosophy of language for the specification of desired intentions in interactions. Our new approach of using communicative acts in high-level models of user interfaces allows their creation with less technical knowledge, since such models are easier to provide than user-interface code in a usual programming language. From one such high-level model, multiple user interfaces for diverse devices are rendered fully automatically using a number of heuristics. A generated user interface for a PDA is already in real-world use and its usability was informally evaluated as good.