Collaboration in the supply chain has been widely discussed, and a wealth of concepts is at hand. Large-scale projects like the Efficient Consumer Response (ECR) in the fast moving consumer goods sector, for example, or Vendor Managed Inventory (VMI) and Collaborative Planning, Forecasting and Replenishment (CPFR) initiatives more generally provide a rich continuum of strategies for collaborating amongst supply chain partners. While individual successful implementations of the latter have already been reported, there has not yet been the widespread adoption that was originally hoped for. In our research, we looked at implementations across several industries and countries, and our findings show that the slow progress to date may be due to a lack of common understanding of these concepts, and the difficulty of integrating external collaboration with internal production and inventory control. In this paper, we set out to classify collaboration initiatives using a conceptual water-tank analogy, and discuss their dynamic behavior and key characteristics. We draw upon case studies from both successful and less successful implementations to illustrate what companies need to do to fully benefit from their collaborative efforts, given their particular circumstances. We conclude that the effectiveness of supply chain collaboration relies upon two factors: the level to which it integrates internal and external operations, and the level to which the efforts are aligned to the supply chain settings in terms of the geographical dispersion, the demand pattern, and the product characteristics.