Most computer users are familiar with the problems of sharing software with others, and the transfer of programs from one computing environment to another. Software represents an ever-increasing proportion of the cost of computing and these costs tend to nullify all the economic advantages flowing from the wider availability of cheap hardware. Years ago it was hoped that the widespread use of high-level programming languages would help in alleviating the problems of software production, by increasing productivity and by making it simpler for users with similar problems to be able to use the same programs, possibly on different types of machines. It is a common experience that in practice this simple optimism has proved to be unfounded. It was these considerations which led us in 1979 to organize a two-week course on "Programming for Software Sharing" at the European Community Joint Research Centre, Ispra Establishment (Italy), forming part of the regular series of "Ispra Courses". With prominent invited lecturers, local contributions and through discussion sessions we examined with an audience from many countries the problems involved in the sharing and transfer of software, as well as suggesting ways of overcoming them. In our local environment we are faced daily with three problems both from engagements in software exchange in the scientific-technical field on a Europe-wide or world-wide basis, and from work with programming techniques and contributions to the international standardization process.