When repetitive inter-organizational transactions are frequent, Electronic Data Interchange (EDI) has become a common approach for business process innovation. As EDI has been utilized as an important means of securing competitive advantage by reducing costs and improving customer service through rapid transaction processing, research has been conducted on EDI success factors, performance, and usage impacts. Previous studies have predominantly focused on research showing that organizational characteristics and system implementation process characteristics affect successful EDI implementation, and that EDI performance is sensitively influenced by the level of EDI usage. However, despite the very close interrelationships among organizational characteristics (organizational size, formalization, centralization, task-EDI fit), system implementation process characteristics (top management support, participation), EDI usage level (usage scope, usage volume), and the outcome variable of EDI performance, there has been virtually no research on a comprehensive model for understanding these factors in an integrated manner. In this regard, this study established a research model incorporating these variables under the assumption that EDI usage level can be inferred as a mediating variable between organizational characteristics and system implementation process characteristics on the one hand, and EDI performance on the other. Specifically, this study aimed to determine whether organizational characteristics and system implementation process characteristics directly affect EDI performance among Korean firms, while also examining whether EDI usage level plays an indirect mediating role in relation to EDI performance. The results revealed that the important factors affecting EDI performance are "centralization," "task-EDI fit," "active top management support," and "participation." "EDI usage scope" was found to mediate the effects of "task-EDI fit" and "participation" on performance, while "EDI usage volume" was found to play a mediating role for "task-EDI fit."