Over the past decade, the policy and scholarly communities have increasingly recognized the need for governance of water-related issues at the global level. There has been major progress in the achievement of international goals related to the provision of basic water and some progress on sanitation services. However, the water challenge is much broader than securing supply. Doubts have been raised about the effectiveness of some of the existing governance processes, in the face of trends such as the unsustainable use of water resources, the increasing pressure imposed by climate change, or the implications of population growth for water use in food and energy production. Conflicts between different water uses and users are increasing, and the state of the aquatic environment is further declining. Inequity in access to basic water and sanitation services is still an issue. We argue that missing links in the trajectories of policy development are one major reason for the relative ineffectiveness of global water governance. To identify these critical links, a framework is used to examine how core governance processes are performed and linked. Special attention is given to the role of leadership, representativeness, legitimacy, and comprehensiveness, which we take to be critical characteristics of the processes that underpin effective trajectories of policy development and implementation. The relevance of the identified categories is illustrated with examples from three important policy arenas in global water governance: the effort to address access to water and sanitation, currently through the Millennium Development Goals; the controversy over large dams; and the links between climate change and water resources management. Exploratory analyses of successes and failures in each domain are used to identify implications and propose improvements for more effective and legitimate action.