This volume is being published for two reasons. The first is to present a collection of previously published articles on the subject of programming methodology that have helped define the field and give it direction. It is hoped that the scientist in the field will find the volume useful as a reference, while the scientist in neighboring fields will find it useful in seriously acquainting himself with important ideas in programming methodology. The advanced student can also study it-either in a course or by himself -in order to learn significant material that may not appear in texts for some time. The second reason for this volume is to make public the nature and work on programming methodology of IFIP Working Group 2.3, hereafter called WG2.3. (IFIP stands for International Federation for Information Processing.) WG2.3 is one of many IFIP Working Groups that have been established to provide international forums for discussion of ideas in various areas. Generally, these groups publish proceedings of some of their meetings and occasionally they sponsor a larger conference that persons outside a group can attend. WG2.3 has been something of a maverick in this respect. From the beginning the group has shunned paperwork, reports, meetings, and the like. This has meant less pUblicity for IFIP and WG2.3, but on the other hand it has meant that meetings could be devoted almost wholly to scientific discussions.

A History of WG2.3.- I: Viewpoints on Programming.- 1. The humble programmer.- 2. Software engineering.- 3. Software engineering-some principles and problems.- 4. The engineering of software: a startling contradiction.- 5. Programs, cities, students-limits to growth?.- 6. On structured programming.- II: The Concern for Program Correctness.- 7. Correctness concerns and, among other things, why they are resented.- 8. An axiomatic basis for computer programming.- 9. Proof of a program: FIND.- 10. An approach to correctness proofs for semicoroutines.- 11. An axiomatic proof technique for parallel programs.- 12. Programming with transition diagrams.- 13. Guarded commands, nondeterminacy, and formal derivation of programs.- 14. A system which automatically improves programs.- III: Harnessing Parallelism.- 15. Towards a theory of parallel programming.- 16. Structured multiprogramming.- 17. Monitors: an operating system structuring concept.- 18. The programming language Concurrent Pascal.- IV: Data Types.- 19. Proof of correctness of data representations.- 20. The algebraic specification of abstract data types.- 21. User-defined types and procedural data structures as complementary approaches to data abstraction.- V: Software Development.- 22. Program development by stepwise refinement.- 23. On a "buzzword": hierarchical structure.- 24. On the design and development of program families.- 25. System structure for software fault tolerance.- 26. Structured analysis (SA): a language for communicating ideas.- References.