During the last few decades, crystallography has become a wide and economically important field of science with many interesting applications in materials research, in different branches of physics, chemistry, geology, pharmacology, biochemistry, electronics, in many technological processes, machinery, heavy industry, etc. Twenty Nobel prizes awarded for achieve­ ments belonging to this· field only underline its distinction. Crystallo­ graphy has become a commonly used term, but - like a whale - it is much easier to recognize than to describe because of an extreme diversity of sub­ jects involved which range from highly sophisticated theories to the develop­ ment of routine technological processes or testing of materials in produc­ tion. It is apparent that only some aspects of selected topics could be included on a single occasion. The conference "ADVANCED METHODS IN X-RAY AND NEUTRON STRUCTURE ANALYSIS OF MATERIALS" held in Karlovy Vary (Czechoslovakia) on October 5-9, 1987, was intended to cover the most important crystallographic aspects of ma­ terials science. The conference was attended by 250 people from 16 countries (Belgium,Bulgaria, China, Czechoslovakia, Finland, France, FRG, GDR, Hungary, Italy, The Netherlands, Poland, Sweden, USA, USSR and Yugoslavia).