In this book we present a collection of papers around the topic of Agent-Mediated Electronic Commerce. Most of the papers originate from the third workshop on Agent{Mediated Electronic Commerce held in conjunction with the Autonomous Agents conference in June 2000. After two previous workshops, one during the Autonomous Agents conference in 1998 in Minneapolis and the second one in conjunction with the International Joint Conference On Arti cial Intelligence in 1999, this workshop continued the tradition of the previous ones by setting the scene for the assessment of the challenges that Agent-Mediated Electronic Commerce faces as well as the opportunities it creates. By focusing on age- mediated interactions, specialists from di erent disciplines were brought together who contribute theoretical and application perspectives in the narrowly focused topic that nevertheless involves wide ranging concerns such as: agent architec- res, institutionalization, economic theory, modeling, legal frameworks and policy guidelines. The main topics for the workshop were: { Electronic negotiation models for agents { Formal issues for agents that operate in electronic market places { Virtual trading institutions and platforms { Trading strategies for interrelated transactions (respectively auctions) The workshop received 12 submissions of which 7 were selected for publication in this volume. Although the number of submissions was less then expected for an important area like agent-mediated electronic commerce there is no reason to worry that this area does not get enough attention from the agent community.