This volume provides the reader with an introduction to system specification and design methods, with particular emphasis on structured and formal methods, method integration, concurrency and safety critical systems. It contains new material by Michael Hinchey and Jonathan Bowen, along with reprints of articles on high-integrity systems. Among these articles are contributions from Leslie Lamport, Nancy Leveson, and C.A.R. Hoare. The text provides details of specification and design approaches for this type of system, an overview of the development process, and evidence of how various classes of high integrity systems may be approached and developed successfully.