User acceptance is one of the key fundamentals for the development of knowledge management systems (KMS). We propose a model of the factors that influence the contribution to KMS repositories in organizations. We use both qualitative and quantitative methodologies to validate a revised unified theory of acceptance and use of technology (UTAUT). We describe a theoretical framework that incorporates the specific facilitating conditions for knowledge management to enhance our understanding of KMS in France. An on line survey conducted with 200 potential contributors showed that performance expectancy and social influence have a significant impact on intentions. Moreover, facilitating conditions such as organizing structure, available time, time allocated, and incentives directly influenced contribution to the KMS. We found no significant effect for socio-demographic variables.