Modern mobile computing paradigms have set new challenges for the development of distributed mobile applications and services. Because of the variability which characterizes the context of such environments, it is important that mobile applications are developed so that they can dynamically adapt their extrafunctional behavior, in order to optimize the experience perceived by their users. This paper proposes an approach for developing adaptive, mobile applications. It is argued that this approach eases the development effort by clearly separating the work required for the development of the application logic from that required for enabling its adaptive behavior. It is argued that in addition to mitigating the development complexity, this approach also enables a new generation of distributed applications. The novelty in the latter is that the applications can dynamically and collaboratively adapt in an ad-hoc manner to improve the quality of the services offered to mobile users.