Stress corrosion cracking, including hydrogen embrittlement, has probably attracted more attention in the last decade than any other single facet of the many that constitute the totality of the environment sensitive behaviour of materials. To some this is because the complex interactions between a number of parameters, particularly metal composition and structure, electrochemistry and the response of a metal to the application of stress, make the subject of stress corrosion fascinating. To others it is be­ cause the subject has become increasingly important in practical terms, as the problem of general corrosion has been controlled and the borderline conditions between widespread attack and com­ plete inactivity are more frequently encountered, and as materials have become more efficiently used by operating at higher stress levels than hitherto. Particularly in advanced engineering systems, such as pressure vessels used in transportation or in the chemical process industries or in the sophisticated equipment used in some of the energy producing industries, the incidence of stress corro­ sion failure has increased alarmingly in recent times and with consequences that are extremely costly if not worse. The reasons for holding a NATO Advanced Study Institute in this field are therefore obvious, but why publish the proceedings of the Institute in an age where there is, arguably, already a VIII superfluity of published material? Obe obvious answer is that the papers presented constitute valuable reviews of detailed develop­ ments in recent times.