Thedesignandanalysisoftradingagentsandelectronictradingsystemsinwhich they are deployed involve ?nding solutions to a diverse set of problems, invo- ing individual behaviors, interaction, and collective behavior in the context of trade. A wide variety of trading scenarios and systems, and agent approaches to these, have been studied in recent years. The present volume includes a number of papers that were presented as part of the Joint International Workshop on Trading Agent Design and Analysis and Agent-Mediated Electronic Commerce which was collocated with the Autonomous Agents and Multi-agent Systems (AAMAS) Conference in Hakodate, Japan, in May 2006. The Joint TADA/AMEC Workshop brought together the two successful and well-established events of the Trading Agent Design and Analysis (TADA) and Agent-Mediated Electronic Commerce (AMEC) Workshops. The TADA series of workshops serves as a forum for presenting work on trading agent design and technologies, theoretical and empirical evaluation of strategies in complex trading scenarios as well as mechanism design. TADA also serves as the main forum for the Trading Agent Competition (TAC) research community. TAC is an annual tournament whose purpose is to stimulate research in trading agents and market mechanisms by providing a platform for agents competing in we- de?ned market scenarios (http://www. sics. se/tac). The AMEC series of wo- shops presents interdisciplinary researchon both theoretical and practical issues of agent-mediated electronic commerce ranging from the design of electronic marketplaces and e?cient protocols to behavioral aspects of agents operating in suchenvironments.