Mobile environments are highly dynamic, characterised by frequent and sudden changes in resource availability. As a consequence, adaptive mobile applications need to be capable of adapting their behaviour to ensure they continue to offer the best possible level of service to the user. Our experience of developing such applications has led us to believe that existing mobile middleware platforms fail to consider adaptive applications on a host as an ensemble of entities competing for the same resources; instead, focusing on the requirements of each application in isolation. A new approach is required which offers the mechanisms to support coordination of the adaptive behaviour of multiple applications in order to achieve a common goal. We present a platform designed to meet this objective. Our platform is based on the notion of the definition of system-wide flexible adaptation policies written using a form of Kowalsky's (1992) event calculus, that may be adapted according to user needs. Moreover, we also believe that by using our approach it will soon be possible to identify and resolve conflicts caused by the need to adapt to multiple contextual triggers.