This chapter describes an architecture for the eMarketplace that integrates the interests of autonomous enterprises in a single open-market environment. The environment encompasses several systems and business issues, such as the many-to-many relationships between customers and suppliers, systems, and business-related services. The architecture for this integrated environment is business-centric and knowledge-oriented. In this architecture, the eMarketplace exists as a collection of economically motivated software agents. The architecture enables and supports common economic services, such as brokering, pricing, and negotiation, as well as cross-enterprise integration and cooperation in an electronic supply-chain. We demonstrate the eMarketplace with two prototype systems.