The IFIP working group 2. 3 (Programming Methodology) is made up of internationally prominent computing academics and industrialists, and broadly its purpose is to invent, discuss and assess new and emerging techniques for improving the quality of software and systems. The group's membership has been influential in topics such as program correctness, object orientation, operating systems and distributed computing; indeed many thriving areas of research nowadays are based on ideas which were once scrutinized by the 2. 3 working committee. This is a volume of chapters written by the membership which will form a reference and guide to the front line of research activity in programming methodology. The range of subjects reflects the current interests of the members, and will offer insightful and controversial opinions on modern programming methods and practice. The material is arranged in thematic sections, each one introduced by a problem which epitomizes the spirit of that topic. The exemplary problem will encourage vigorous discussion and will form the basis for an introduction/tutorial for its section.