This study examines which factors are urging Korean companies to participate in e-marketplaces. By adding interorganizational factors, we extended an innovation-theory-based research model that is often applied to study the information technology adoption. 71 questionnaires from 720 Korean manufacturing companies were collected. Independent variables of the research were environmental, organizational, innovation, and interorganizational characteristics. We found that the environmental characteristics, innovation characteristics, and interorganizational characteristics have insignificant effect on the participation of domestic companies in e-marketplaces whereas the organizational characteristics have significant relationship with the participation in e-marketplaces. The result implies that many Korean companies take wait-and-see strategy in the forming stage of e-marketplaces, However, IT infrastructure and the support of top management for IT play very important role in adopting e-marketplaces.