This exploratory research makes a first attempt at building a comprehensive model of the drivers of internal integration. A series of case studies are used to develop a more complete understanding of the factors that enable and inhibit efforts at building integration across operations, purchasing and logistics. The results suggest that this is a complex phenomenon driven by a number of factors including the structure and culture at the plant, reward systems and the amount of formal and informal communication across the functions. The end result of the research is a testable model of how integration can be built across these three key internal supply chain functions.