Both local knowledge and modern (more usually Western) science can be valuable inputs to environmental Disaster Risk Reduction (DRR) policies if they are given equal weight. Local knowledge for DRR is important in countries where government capabilities are very limited and where long-standing traditions of natural resource management still exist and can be used for governance. Modern science can add value by expanding the knowledge base using methods not available to local people, connect empirical evidence to theory, and use theory in data-poor locations to fill empirical gaps. While the need for the use of both knowledge systems has been advocated for some time, there is little published material from which to learn. Timor Leste is an impoverished nation prone to disasters from the connected threats of floods and landslides and human vulnerability because of dependence for settled agriculture and some villages on floodplains and deltas, which are susceptible to floods, and hillslopes for shifting agriculture, which are susceptible to landslides. In this paper the results of focus group discussions with local people in the catchments of the Laclo and Caraulun rivers are compared with results from modern science. Local people thought more widely than the scientists, drawing particularly on their concerns with aquatic resources, but within the realm of erosion, river sedimentation and flooding, the local people and scientists reached similar conclusions about causes and consequences of the threats. The major difference between the two knowledges is that the local people simultaneously held ‘naturalist’ and ‘mythological’ explanations of disasters, along with their attribution of disasters to the failure to put to rest the spirits of the many people killed during 400 years of Portuguese colonization, Japanese occupation during the Second World War, 25 years of brutal occupation by Indonesia, and the mayhem caused by militias after independence. Public policy for DRR is likely to be most successful if both forms of knowledge are embedded in the traditional governance system called tarabandu and ceremonies held to settle the spirits of the dead that could also be used to develop an integration strategy for the two sources of knowledge for catchment management. The 2005 National Disaster Risk Management Plan includes Community Based Disaster Risk Management but does not mention tarabandu. Successful DRR, in places where local knowledge and traditional practices survive, could incorporate a much wider range of information and approaches than is usually included in schemes designed by Western ‘experts’.