This paper develops a theoretical model to explain the relationships between knowledge management and business value in IT-enabled business projects. It draws upon a wide range of literatures including project management, management information systems, software engineering, organization and management theory, organizational behaviour and strategy. The overall model comprises two sub-models. The first shows how the alignment of three project-based knowledges directly influences business value. The second shows how four knowledge-based concepts, knowledge management, knowledge stock, enabling environment, and knowledge practices, combine to create the project-based knowledges. Together these two sub-models provide an overall model of the causal system through which knowledge management influences business value. This research makes contributions to the research into IT Projects by (1) integrating fragmented literatures which connect knowledge management and project success; and (2) proposing for discussion a predictive model in which knowledge management influences business value. It has the potential when further developed to clarify what project managers can do to manage knowledge in a systematic way.