What does it take to build a successful knowledge management system (KMS)? Knowing the essential success factors is useful as it provides researchers and practitioners with the basic requirements for building a successful KMS. Also, if we take a Churchman (1979) view of systems, it can be argued that determining KMS success factors will also help us determine KM initiative success factors as Churchman found it difficult to separate the system from the process requiring the system. However, what is KM or KMS success? The literature does not provide a consensus on this, although two concepts of success can be identified. The first considers KM or KMS a success if knowledge use through the initiative or system improves the organization’s ability to compete. The second considers KM or KMS a success if the KM processes implemented through the KMS (discussed later) are implemented effectively. Both success concepts imply that the KMS has to be used. Therefore, KM and KMS success factors are those factors that encourage or help users to use the KMS to effectively perform KM functions.