This book presents recent thought on market efficiency, using a complexsystems approach to move past equilibrium models and quantify the actualefficiency of markets. The older view that markets are perfectly efficient hascome under attack from several different directions, including studies of marketanomalies, human psychology, bounded rationality, agent-based modeling, andevolutionary game theory. This volume brings together some of the besteconomists, physicists, and biologists working on quantitative models ofcomplex, self-organized behavior relevant to measuring marketing efficiency, tostimulate new approaches to understanding financial markets.