Computational Economics 18: 25–48, 2001. © 2001 Kluwer Academic Publishers. Printed in the Netherlands. 25 Self Organization and Coordination SCOTT E. PAGE Center for Study of Complex Systems, University of Michigan, Ann Arbor, MI 48106, U.S.A.; e-mail: spage@umich.edu Abstract. In this paper, I analyze the organization of tasks or activities by a collection of agents. I begin by formally defining organized collections and robustly organized collections of agents in the context of a simple model. Within this framework, I demonstrate that organized collections and robustly organized collections exist and equilibria need not be organized. I then test whether adaptive agents can self-organize in this environment. I find that simple behavioral rules can lead to nearly organized, fairly robust collections of agents. Key words: self-organization, coordination, equilibrium Tens of millions of people making billions of decisions every week about what to buy and what to sell and where to work and how much to save and how much to borrow and what orders to fill and what stocks to accumulate and where to move and what schools to go to and what jobs to take and where to build supermarkets and movie theaters and electric power stations, when to invest in buildings above ground and mine shafts underground and fleets of trucks and ships and aircraft – if you are in a mood to be amazed, it can amaze you that the system works at all. Thomas Schelling Micromotives and Macrobehavior (p. 21) 1. Introduction While long thought to require planning, order can also arise spontaneously. Birds form flocks, water particles swirl in eddies, and pedestrians in crowded train sta- tions form rivers of traffic. This phenomenon is often referred to as ‘order from the bottom-up’. Recently, scientists have attempted to explain this emergence of self-organized behavior using agent based models. Given the importance (and pre- valence) of order in the economy, explaining it geographically (Krugman, 1996) and temporally have grown as research topics within economics (Kirman, 1997; Arthur and Durlauf, 1997).