This paper examines how an organization can use information technologies, in the form of a knowledge management system (KMS), to leverage the knowledge base of the firm. This paper proposes that one aspect of knowledge management is the capture and integration of intellectual capital, residing in a firm’s employees, through the expansion of social capital, residing at the level of the firm. Based on this proposition, the success of a knowledge management system can be measured. A model of KMS Success is developed drawing from literature in the fields of information systems and strategic management. This model proposes that there are three main components to determine KMS success: system quality, knowledge quality, and organizational environment. A theory is presented that predicts if the technology and the knowledge fit the needs of the users, and if there is proper alignment of the organizational environment, the result will be high system usage. KMS success, a measure of the increase in the firm’s social capital, can be determined by examining system usage.