Refinement is the term used to describe systematic and formal methods of specifying hardware and software and transforming the specifications into designs and implementations. The value of formal methods in producing reliable hard-and software is widely appreciated by academics and workers in industry, despite the fact that certain research areas, such as the application to industrial-scale problems, are still in their infancy. This volume contains the papers presented at the 5th Refinement Workshop held in London in January 1992. Its theme was the theory and practice of software specifications, which is the transformation of formal software specifications into more correct specifications, designs and codes. This has been an important area of research for the last 5 years and the workshop addressed specific issues and problems related to it. Among the topics discussed in this volume are: the role of refinement in software development, parallel designs and implementations, methods and tools for verifications of critical properties, refinement and confidentiality, concurrent processes as objects, the compliance of Ada programmes with Z specifications and a tactic-driven refinement tool.