Describes a case study of supply chain collaboration facilitated by a decision support environment in a high-tech electronics supply chain with multiple independent companies. In a business process called collaborative planning, representatives from these companies jointly take decisions regarding production and shipments for a large part of their collective supply chain. Particular attention is given to the interactions between levels of partner trust and information transparency on the one hand, and resulting improvements in supply chain performance on the other. The importance of hard work in developing the work flows necessary to support this joint planning process in starting a virtuous cycle of steadily increasing levels of all these aspects of supply chain collaboration is stressed. A theoretical model of the interactions between these aspects is presented, based upon a review in the literature. This model is then explored in an analysis of the collaborative planning case. Contains suggestions for further research and managerial recommendations.