This 2-volume work represents the proceedings of the First European Workshop on Fault Diagnostics, Reliability and Re- lated Knowledge-Based Approaches held in the Island of Rho- des, Greece (August 3l-September 3, 1986). This Workshop was organized in the framework of a joint research project spon- sored by the Commission of the European Communi ties under the Stimulation Action Programme. The principal aim of the Workshop was to bring together people working on the numeric and symbolic (knowledge-based) treatment of reliability and fault diagnosis problems, in order to promote the interaction and exhange of ideas, expe- riences and results in this area. The workshop was a real success, with SS papers presen- ted and 70 participants. A second Workshop of the same na- ture has been decided to be held in Manchester (UMIST), - gland, in April 1987. . The two volumes contain sufficient amount of informa- tion which reflects very well the state-of-the-art of the field, and shows the current tendency towards knowledge-ba- sed (expert systems) and fault-tolerant approaches. Volume 1 contains the contributions on fault diagnostics and reliability issues (numeric treatment), and Vo*lume 2 the contributions on knowledge~based and fault-tolerant techni- ques. We are grateful to the Commission of the European Com- munities for having sponsored the Workshop, and to all au- thors for their high quality contributions and presenta- tions.