The potentialities of specialized languages, in comparison to those of other types of specialized systems, are discussed. The point is made that these languages have been invented by information processing professionals in order to assist the problem-solving activities of computer users by providing them with appropriate interfaces to the computer, with languages natural to their own view of reality. The nature of today's ubiquitous applications packages are examined, and the characteristics of the environments which support these languages are discussed. Finally, some experiences with the Rapidly Extensible Language (REL) system are presented. (Author/PB)