This book constitutes the thoroughly refereed post-proceedings of the First International Symposium on Unifying Theories of Programming, UTP 2006, held at Walworth Castle, County Durham, UK, in February 2006. The book presents 14 revised full papers. Based on the pioneering work on unifying theories of programming by Tony Haare and Jifeng He, UTP 2006 focused on the most significant results and raised awareness of the benefits of unifying theoretical frameworks.

IFM 2000, the second in a series of international conferences on Integrated F- mal Methods, was held at the 18th-century chateau DEGREES of Schloss Dagstuhl, Sa- land, Germany, from the 1st to the 3rd of November 2000. The conference programme consisted of invited talks from Sir Tony Hoare FRS and Wolfram Schulte, along with 22 papers selected from 58 submissions. Applying formal methods may involve the modelling of di erent aspects of a system that are expressed through di erent paradigms. This motivates us to research the combination of di erent viewpoints of a system, either by the creation of hybrid notations, by extending existing notations, by translating between notations, or by incorporating a wider perspective with the innovative use of an existing notation. The integration of formal methods promises great bene ts to systems - delling and software development. Regardless of the approach taken, however, signi cant issues can arise in areas such as semantic integration, the tracta- lity of our notations, the integration of tool support, the integration of proof systems, consistency, and completeness. Issues arise equally in our conceptua- sation of systems at di erent levels of abstraction and the development of these conceptualisations through the process of re n