There has been an increasing use of the word ‘emergence’ in architecture, but as of yet there has not been a systematic investigation of its instruments, nor has there been any real attempt to go beyond the common, but vague, definition of emergence as the properties of a system that cannot be deduced from its parts. Emergence is a consolidation of a paradigm shift that began more than 80 years ago, a profound change that has blurred the boundaries between once quite separate sciences, and which has changed industry. It has made potent changes to the technological world, changes that demand a new way of thinking about architecture and substantial changes to the way we produce it. Emergence does not await a practice and defies conventional categorisation as either theory or practice. Emergence is both an explanation of how natural systems have evolved and maintained themselves, and a set of models and processes for the creation of artificial systems that are designed to produce forms and complex behaviour, and perhaps even real intelligence. The impact of emergence on architecture has significant potential, and an important shift towards the new paradigm and its techniques of evolution and morphogenesis is already under way. This issue of focuses on these methodologies, on experimentation and on the development of new instruments of design.