The design and analysis of electronic commerce systems in which agents are - ployed involves finding solutions to a large and diverse array of problems, concerning individual agent behaviors, interaction, and collective behavior. A wide variety of electronic commerce scenarios and systems, including agent approaches to these, have been studied in recent years. These studies suggest models that support the - sign and the analysis at both the level of the single agent and the level of the multiagent system. th This volume contains revised, selected papers from the 10 Workshop on Agent- Mediated Electronic Commerce (AMEC-X), co-located with the 7th International Joint Conference on Autonomous Agents and Multiagent Systems (AAMAS 2008), th and from the 6 Workshop on Trading Agent Design and Analysis (TADA), - located with the 23rd AAAI Conference on Artificial Intelligence (AAAI 2008). The primary, and complementary, goal of both workshops was to continue to bring - gether novel work from diverse fields that focus on modeling, implementation, and evaluation of computational trading institutions and/or agent strategies.