Interorganizational knowledge sharing is critical to knowledge intensive collaborations between organizations. Despite a proliferation of literature on knowledge sharing, most studies focused on such practice within an organization. The question of how to achieve effective interorganizational knowledge sharing remains unanswered. This study intends to answer this research question using the results from a case study of a software implementation project. Collaboration between software vendors and clients in information systems development/implementation projects require considerable amount of knowledge exchange between the partners. Differences in organizational culture, knowledge domain, as well as other critical factors, pose major challenge for inter-organizational knowledge sharing. To be able to observe the impact of these critical factors on interorganizational knowledge sharing, the knowledge sharing processes between organizations should first be thoroughly explored. While effectiveness of knowledge sharing may be viewed from different theoretical disciplines, we draw our analysis based on organizational learning perspective.