ABSTRACT: Cars Hommes is professor of Economic Dynamics at the Center for Nonlinear Dynamics in Economics and Finance (CeNDEF) in the Faculty of Economics and Business at the University of Amsterdam. He is one of the pioneers in complexity economics. His work on nonlinear complex economic systems challenges the traditional neoclassical paradigm of the representative rational agent in economics. In a rational world the economy is characterized by an average agent (consumer, producer, investor, etc.), who is a perfect optimizer with rational expectations about the future. His work develops an alternative complexity paradigm based on agent-based behavioral complexity models. His Center for Nonlinear Dynamics in Economics and Finance (CeNDEF) is a multi-disciplinary research center in complexity economics. CeNDEF not only has developed an alternative theory of complex economic systems, but has tested this alternative paradigm successfully in laboratory experiments with human subjects and estimated complexity models using financial and macroeconomic data sets. Cars is one of the organizers of the workshop Socio-Economic Complexity that is being held in the Lorentz Center from 23 March through 27 March.