This book constitutes the proceedings of the First International Workshop on Traffic Monitoring and Analysis, TMA 2008, held in Aachen, Germany, on May 11, 2008 in conjunction with the IFIP Networking 2008 conference. The workshop is an initiative from the COST Action IC0703 "Data Traffic Monitoring and Analysis: Theory, Techniques, Tools and Applications for the Future Networks." The 15 papers contained in this volume were carefully reviewed and selected from 34 submissions. They encompass research areas related to traffic analysis and classification, measurements, topology, discovery, detection of specific applications and events, packet inspection, and traffic inference. The papers are organized in topical sections on QoS measurement, rupture detection, traffic classification, as well as traffic analysis and topology measurements.