The Multi-Agent-Based Simulation (MABS) workshop is the eleventh of a series that began in 1998. Its scientific focus lies in the confluence of social sciences and multi-agent systems, with a strong application/empirical vein, and its emphasis is stressed on (i) exploratory agent based simulation as a principled way of undertaking scientific research in the social sciences and (ii) using social theories as an inspiration to new frameworks and developments in multi-agent systems. The excellent quality level of this workshop has been recognized since its inception and its proceedings have been regularly published in Springer's Lecture Notes series. MABS 2010 will be hosted at AAMAS 2010, the 9th International Conference on Autonomous Agents and Multiagent Systems, which will take place in Toronto, Canada, on May 10-14, 2010.