Description:This book constitutes the thoroughly refereed post-proceedings of the 6th International Workshop on Agent-Mediated Electronic Commerce, AMEC 2006, held in New York, NY, USA in July 2004 as part of AAMAS 2004. The 15 revised full papers presented were carefully selected from 39 submissions during two rounds of reviewing and revision. The papers bring together novel work from such diverse fields as Computer Science, Operations Research, Artificial Intelligence and Distributed Systems that focus on modeling, implementation and evaluation of computational trading institution and/or agent strategies over a diverse set of goods. They are organized in topical sections on mechanism design, trading agents, and tools.