As international political and economic relations have become increasingly complex, so have the pressures on international boundaries and the borderlands which surround them. Although there are still many examples of "traditional" boundary problems associated with disputes between states concerning control over territory and maritime space, the papers in this volume demonstrate the vulnerability of borderlands to other forces, most notably illegal immigration and cross-border crime. This study aims to investigate the causes and implications of borderland stress. The first section explores changing concepts of sovereignty and their impact on the meaning and functions of international boundaries. The contributions in the second and third sections offer a combination of regional appraisals and individual case studies highlighting the range of problems affecting borderlands around the world, together with an assessment of some of the initiatives launched in response to those problems. While many of the conclusions drawn are rather sobering, it is clear that in some parts of the world new and imaginative approaches to territorial organization and management are helping to create safer, more dynamic and more prosperous borderlands. The papers in this volume represent the proceedings of the fifth International Conference of the International Boundaries Research Unit, held at the University of Durham on 15-17 July 1998.