The Okavango River system flows through Angola, Namibia and Botswana. It is in near-natural condition and supports globally iconic wetlands and wildlife. The basin's people are poor and development is inevitable: the next decade is critical. The river could become an example of responsible planning that resolutely addresses the three pillars of sustainable development. Recognizing this, the Member States completed a transboundary diagnostic analysis (TDA) in 2010 funded by the three governments and the Global Environment Facility. A central feature of the TDA was a basin-wide environmental flow assessment using the DRIFT (Downstream Response to Imposed Flow Transformation) holistic approach. This produced scenarios of increasing water resource use that spelled out the costs and benefits in terms of the health of the river ecosystem, associated social structures and local and national economies. The results were used to help create a transboundary strategic action programme, which the Member States are now beginning to act on. This article describes the DRIFT application, the findings and how these could be used to help achieve sustainable development. Keywords: Okavango River, holistic environmental flows assessment, DRIFT, transboundary diagnostic analysis, strategic action programme, flow indicators, Okavango.