This book contains 18 invited contributions to the first Inter national Symposium on Order-Disorder Transformations in Alloys+. They cover the major aspects of this group of phase transformations. Although structural order-disorder transformations have been investigated for over 50 years the invited papers, the research papers - whose titles and authors are listed in the appendix - and the discussions at the Symposium have demonstrated very active continued interest and con siderable recent progress in the subject. This is true for theoretical work as weIl as for experimental studies and for...