This book constitutes the thoroughly refereed post-proceedings of the Second International Workshop on Privacy Enhancing Technologies, PET 2002, held in San Francisco, CA, USA, in April 2002. The 17 revised full papers presented were carefully selected during two rounds of reviewing and improvement. Among the topics addressed are Internet security, private authentication, information theoretic anonymity, anonymity measuring, enterprise privacy practices, service architectures for privacy, intersection attacks, online trust negotiation, random data perturbation, Website fingerprinting, Web user privacy, TCP timestamps, private information retrieval, and unobservable Web surfing.