The proceedings of the Second US-Italy Seminar on Variable Structure Systems is published in this volume. Like the first seminar, its conception evolved from common research interests on bilinear systems at the Istituto di Automatica of Rome University and at the Electrical and Computer Engineering Department of Oregon State University. Again, the seminar was focused on variable structure systems in general. In this case, however, emphasis is given to applications in biology and economics along with theoretical investi gations which are so necessary to establish a unified theory and to...