Future ubiquitous computing environments are likely to consist of numerous interacting components, many of which will have been developed in isolation from each other. Unless appropriate measures are taken, interference (where a component's behavior in a deployed system differs from its behavior when in isolation) is likely to be commonplace. In this paper we explore the importance of this problem and present our work-in-progress on a framework that enables designers, developers, and researchers to describe and thus reason about interference in ubicomp environments.