The topic of "structural control", which had already experienced some attention through publications, for example by Roorda, Yao, Yang, Abdel-Rohman, Leipholz etc. , mostly in journals of ASCE, was given its fIrst international forum at the University of Waterloo, Waterloo, Ontario, Canada, via an ruTMf - Symposium held in June, 1979. This very successful event gathered experts from a variety of technical and theoretical domains in which control plays tradi­ tionally an essential role and was meant to present the new idea of structural control to a broad audience, thus triggering interest and commitment as well as cross-fertilization. However, the peculiarities of structural control were already sumciently well pointed out and stressed by those participants of the symposium who had devoted themselves earlier to this specwc topic for some time. The result of presentations and discussions are collected in a set of Proceedings entitled "Structural Control", published by North - Holland Publishing Company and the Solid Mechanics Division (SMD) of the University of Waterloo. The stimulation following this fIrst symposium was quite noticeable in the literature and led to the conviction of many researchers that after a reasonable period of time, a second meeting should be held to collect the fruits produced by the intermediate efforts of those working with increased emphasis on structural control. Therefore, Professors J. T. P. Yao, Department of Civil Engineering, Purdue University and H. H. E.