The Forum on Sustainable Futures for Australia’s Tropical Rivers was held at Charles Darwin University in Darwin in February 2004. The concept emerged in response to increasing social, political and business interest in the water resources of northern Australia, recognising the need for science to be proactive in providing the knowledge to guide current and future policy and decision making on the use of these rivers. Pressures on tropical systems worldwide are increasing and Australian systems are not isolated from this reality.The papers within this issue focus onAustralia, but the lessons learned and conclusions drawn are relevant to many parts of the world. There is a long history of interest in development of northern Australia and this is currently being fuelled by increasing pressure on water supply and river systems in southern regions. Tropical rivers and groundwater systems contain roughly 70% of Australia’s freshwater resources. Water availability has been the driver of many grand schemes in the past and there are many examples that have proven to be non-feasible, or which have had significant unforeseen environmental impacts. Further development of water resources in tropical Australia is likely to result in conflicting opinions concerning risks to environmental goods and services and cultural values, as well as the intended social and economic benefits. Land use across the Australian tropical region is dominated by grazing, agriculture, Aboriginal tenure and traditional use, mining and tourism, with significant fishing interests in estuaries and coastal waters. Current management priorities are focussed on water-resource planning, water quality, fisheries, invasive plants, salinity, conservation, grazing and fire management. Outside of catchments such as the Ord and Burdekin, which have existing irrigation areas, estimates of existing water use as a percentage of sustainable yield are low. Scientific understanding of rivers in southern Australia has largely developed in a reactive fashion as unforeseen consequences of earlier development decisions have become apparent. While some tropical catchments have been extensively developed and are now the focus of environmental management efforts, many catchments are relatively unchanged from their historical condition under traditional ownership. The combination of growing interest in water at a national level, development aspirations in the tropics and the relatively good ecological condition of tropical rivers provides an opportunity for science to lead the information needs for sound management of Australia’s tropical rivers into the future. The objectives of the forum were to assemble and synthesise existing scientific knowledge of Australia’s tropical river systems and to identify critical knowledge gaps for future research priorities. The forum covered catchments spanning tropicalAustralia from Broome in WesternAustralia to Rockhampton in Queensland, adopting a system-scale approach to the functioning of tropical rivers, their wetlands, floodplains, estuaries and near-shore environments, and the impacts of land use, water use and other activities. Forum themes covered present and future use and management of tropical rivers, aquatic ecosystem assets and threats, tropical aquatic ecosystem processes, the role of flow and connectivity in tropical rivers and information needs to protect tropical rivers in the face of increasing development pressure. Erskine et al. (2005) review the geomorphological template of tropical Australian rivers and present a detailed typology of characteristic reaches. The template provides a sequential spatial framework for the ecological function of tropical rivers, with clear implications for the fish communities likely to be encountered in each region. Wetlands are characteristic geomorphic habitat features of tropical Australia that support high levels of biodiversity, but large areas of wetlands have been lost or are under threat from human activities in some regions. Finlayson et al. (2005) offer an analysis of the drivers behind the changing face of tropical wetlands, including both direct drivers and the less direct social attitudes that encourage or allow wetlands to be degraded. They propose a model based on inventory, assessment and monitoring to maintain the character of tropical