A system and methods are described for providing a fully automated, requisition-driven, "Just-In-Time" supply-based, centralized e-procurement system, suitable for governments or entities with similar procurement needs. A Web site-based reverse-auction among competing authorized suppliers is employed for purchase of all goods and services, except those that must be procured by other means. Automated methods are provided for: requisition handling and pooling; order formulation; processing and tracking; consolidated, distributed and other shipping arrangements; procurement accounting and payment authorization; supplier-relations administration; centralized e-procurement catalog management; procurement data analysis, and report and alert generation; procurement-needs analysis; and inventory management. A structure of internal and external modules is created for security. To the extent possible, all communication from and to and within the system is performed digitally.