The purpose of this paper is to understand the impact of cooperative purchasing on buyers’ purchasing power. Purchasing in the humanitarian sector has traditionally been characterized by a low level of coordination due to inter-agency competition for funding, diverging mandates and other organizational differences. Relationships with commercial suppliers have also remained arm's-length and often dormant due to high levels of uncertainty and strict public procurement rules and regulations. However, recent pushes for increased efficiency and effectiveness are driving humanitarian agencies toward cooperative purchasing – a purchasing strategy that is claimed to be highly beneficial for members of the purchasing consortium not least for its ability to increase buyers’ purchasing power. In reality, the effectiveness of the strategy in increasing purchasing power is unclear.