This book constitutes the refereed proceedings of the 9th International Conference on Passive and Active Measurement, PAM 2008, held in Cleveland, OH, USA, in April 2008.

The 23 revised full papers presented were carefully reviewed and selected from 71 submissions. The papers focus on research and practical applications of network measurement and analysis techniques and are organized in topical sections on addressing and topology, applications, classification and sampling, measurement systems and frameworks, wireless 802.11, tools, characterization and trends, and malware and anomalies