Scalable computing will, over the next few years, become the normal form of computing. In this paper we present a unified framework, based on the BSP model, which aims to serve as a foundation for this evolutionary development. A number of important techniques, tools and methodologies for the design of sequential algorithms and programs have been developed over the past few decades. In the transition from sequential to scalable computing we will find that new requirements such as universality and predictable performance will necessitate significant changes of emphasis in these areas. Programs for scalable computing, in addition to being fully portable, will have to be efficiently universal, offering high performance, in a predictable way, on any general purpose parallel architecture. The BSP model provides a discipline for the design of scalable programs of this kind. We outline the approach and discuss some of the issues involved.