An International Symposium on Defects and Fracture was held in Tuczno, Poland, 13-17 October 1980 under the sponsorship of the Polish Academy of Sci ences and Institute of Fracture and Solid Mechanics, Lehigh University. Profes sor H. Zorski of the Academy and Professor G. C. Sih of Lehigh University were Co-Chairmen. The idea for the Symposium was initiated by the members of the Organizing Committee: G. C. Sih (Co-Chairman), H. Zorski (Co-Chairman), M. Matczynski (Secretary), D. R. Axelrad, R. Bullough, J. W. Provan and R. deWit. With the rapid development of high performance materials and their increasing use in vital structural applications, there is a need for a more in-depth under standing of the fundamentals associated with material behavior and failure. Al though this topic encompasses a wide range of disciplines, it is appropriate to narrow the discussion to material failures initiating from inherent, unavoidable defects or cracks. A balanced coverage of analysis and physics was achieved by inviting speakers with backgrounds in applied mechanics and solid state physics. The input was limited to a small group of specialists who had the opportunity to discuss not only past progress but also ideas for future research."