Modern software development practices show that there is significant diversity in the product, process and geographical location of software development due to economical, technical and logistical constraints. Such diverse development demands flexibility in the software engineering methodology. In this paper, we propose the Cellular Development Methodology (CDM), an architecture-driven approach to flexible software development. CDM derives the development process and its architecture from the software architecture of product. The software development process is structured and customised as a network of cooperating cells. Our contribution is a cellular approach to software development based on the software architecture of the end product whereby a network of configurable cells yield customisable, potentially distributed software development processes which in turn produce software that is highly tailored to user requirements.