This paper assesses the decentralization processes and performances of river basin management decentralization in Sub-Saharan Africa, using primary data from 27 river basins in the region. The main findings are that water scarcity is a major stimulus to reform; that water user associations, if not well prepared and trained, may deter the decentralization process; and being part of an existing treaty over an international basin helps foster the process. Conditions improving decentralization performance include: scarcity of water resources, longer period of implementation, bottom-up creation, and appropriate budgetary support of the river basin organization. Findings are relevant for policy in decentralization in remaining river basins across the continent and elsewhere, suggesting important central government interventions and an implementation sequence that would lead to more effective results.