Researchers and practitioners have reported on the factors said to influence the design and implementation of Knowledge Management Systems (KMS). Factors such as strategy, culture, information technology, people and organisational structure have arisen as key dimensions to be considered in KMS implementation. However, researchers have tended to explore these factors in isolation, and have, by and large, achieved little in the way of success in establishing relationships between them. Using a research framework derived from the literature, this paper investigates the key factors affecting the implementation of KMS and explores the links between these factors. A field study approach incorporating 12 large organisations that have implemented KMS is adopted to study the phenomenon. Significantly, feedback from KM practitioners provided direct guidance on the model’s practical relevance and led to a refined and extended model of KMS implementation factors. Hence, the findings provide a foundation for understanding the key factors that organisations face as they implement Knowledge Management Systems.