A firm’s internal supply chain refers to the specific value-creating functions within the organisation, such as production, sales and distribution. Previous research has shown that these functions need to work together to achieve high levels of firm performance. However, the means to achieve this integration of internal supply chain functions have not received much attention in the current literature. In this paper, we review the published literature on internal supply chain integration and report on empirical research, which we conducted to test various antecedents of integration. Results from our survey indicate that line managers are able to improve functional integration by fostering a positive attitude towards other departments. Integration appears also to be enhanced by making departments jointly accountable for achieving company goals.