A number of formal notations and theories have now emerged and proved themselves effective as tools for the practising software engineer. Within these theories we see a number of common themes, such as abstraction, refinement, choice, termination, feasibility, concurrency and communication. The commonality of such themes opens perspectives for unifying theories, an activity which can increase our ability to use existing methods and notations, to recognise their limitations, and to extend and generalise them. Based on the pioneering work on unifying theories of programming of Tony Hoare and He Jifeng, which itself acknowledges the influence of Eric Hehner's seminal ideas on predicative programming, the aims of this Symposium are to reaffirm the significance of the ongoing UTP project, to encourage efforts to advance it by providing a focus for the sharing of results by those already actively contributing, and to raise awareness of the benefits of such unifying theoretical frameworks among the wider computer science and software engineering communities.