A s everyone knows, computer networks play an increasingly important role in the economy: in the daily operation of big firms, the smooth running of government agencies, and transactions in financial markets. However, it may surprise even professional economists to find that economics is of help in allocating computational resources to programs that run in these systems.The reason is that computer networks can be regarded as a community of concurrent processes, or a "computational ecosystem" (Huberman and Hogg, 1988). As these networks grow, they become analogous to human market economies because the processes-in their interactions, strategies, and lack of perfect knowledge-face the same issues as people in a market. This paper will explain this analogy and explore one of its main implications: that economics may offer new ways to design and understand the behavior of these emerging computational systems. In particular, markets provide examples of methods to deal successfully with coordinating asynchronous operations in the face of imperfect knowledge. A computational system set up along market rules can allow the system as a whole to adapt to changes in the environment or disturbances to individual members. In what follows we will describe how market-based computational systems are already working and how they may sometimes break down. Some of the best-known programs already using these ideas include computational resource allocation (Malone et al., 1988;Waldspurger et al., 1992;Nash, 1993) and thermal markets for controlling building environments (Clearwater and Huberman, 1993), which have shown increased performance when compared with traditional operating systems.