The monograph presents the proceedings of the Third Symposium on Empir ical Foundations of Information and Software Sciences (EFISS) held at the Riso National Laboratory in Roskilde, Denmark, 23-25 October 1985. The EFISS series of meetings was initiated with the express purpose of explor ing subjects and methods of scientific inquiry of empirical nature which are of common interest to information and software sciences. Furthermore, these meetings were expected to provide a cross-disciplinary forum for discussion of problems and exchange of research results of importance for the design and application of advanced information systems. The previous two EFISS symposia took place at the Georgia Institute of Technology in Atlanta, Georgia, USA. The first meeting in 1982 focused on methods of experimental design and measurement techniques in information and software sciences. The second meeting was held in 1984 and its main theme was the value of information in prescriptive contexts, such as value of information for understanding and implementation of these messages, instructions, and commands. Specific examples of problems of this kind are the value of comments for the enhancement of understanding of computer programs, the value of information in assisting and guiding users of on line interactive systems, and the value of lexical aids in information retrieval. In both symposia, contributed papers were considered on any other valid subject of empirical foundations of the said two sciences.