The more our society relies on electronic forms of communication, the more the security of these communication networks is essential for its well-functioning. As a consequence, research on methods and techniques to improve network security is extremely important. Topics in this volume include the latest developments in: Security protocols; Secure software engineering; Mobile agent security; E-commerce security; Security for distributed computing. ?/LIST? Advances in Network and Distributed Systems Security contains the proceedings of the First International Working Conference on Network Security (I-NetSec 01), which was sponsored by the International Federation for Information Processing (IFIP), and held in Leuven, Belgium in November 2001. This volume will be essential for researchers and practitioners working in this fascinating and fast-evolving field.