This volume contains eighteen selected papers presented at the Second International Conference on Stochastic Structural Dynamics, which are related to new theoretical developments in the field. This and a companion volume, related to new practical applications, constitute the proceedings of the conference, and reflect the state of the art of the rapidly developing subject. The conference was held in Boca Raton, Florida during May 9-11, 1990 hosted by the Center for Applied Stochastics Research of Florida Atlantic University. A total of 20 technical sessions were organized, and attended by eighty participants from 12 countries. Special emphases of the conference were placed on two areas: applications to earthquake engineering and stochastic stability of nonlinear systems. Two sessions were dedicated to the memory of late Professor Frank Kozin, one of the founders and most active contributors to the stochastic stability theory. We are indebted to the National Center for Earthquake Engineering Research (NCEER) for financial support. Most credit belongs to each of the authors whose contributions were the very basis for the undoubted success of the conference. We are grateful to the reviewers who carefully refereed the contributions for these two volumes. Our special thanks are due to Mrs. Christine Mikulski, who carried out all the necessary secretarial tasks associated with the conference with dedication.