The task of producing policies for the management of Earth’s natural resources is a problem of the gravest concern worldwide. Such policies must address both responsible use in the present and the sustainability of those finite resources in the future. Resources are showing the adverse results of generations of exploitation, and communities fail to see the outcomes of past policies that have produced, and continue to produce, these results. They have not learned from past policy failures, and consequently fail to produce natural resource management (NRM) policies that support sustainable development.¶ It will be argued that NRM policy makers fail to learn from the past because they do not have a good historical perspective and a clear understanding of the dynamics of the complex human-environment system that they manage. It will also be argued that historians have not shown an interest in collaborating with policy makers on these issues, even though they have much to offer. Therefore, a new approach is proposed, which brings the skills and understanding of the trained historian directly into the policy arena.¶ This approach is called Applied Environmental History (AEH). Its aims are to help establish an area of common conceptual ground between NRM practitioners, policy makers, historians and dynamicists; to provide a framework that can help NRM practitioners and policy makers to take account of the historical and dynamical issues that characterise human-environment relationships; and to help NRM practitioners and policy makers improve their capacity to learn from the past. Applied Environmental History captures the characteristics of public and applied history and environmental history. In order to include an understanding of feedback dynamics in human-environment systems, it draws on concepts from dynamical systems theory. Because learning from the past is a particular form of learning from experience, AEH also draws on theories of cognitive adaptation.¶ Principles for the application of AEH are developed and then tested in an exploratory study of irrigation development that is focused on the NRM issue of salinity. Since irrigation salinity has existed for centuries, and is a serious environmental problem in many parts of the world, it is a suitable NRM context in which to explore policy makers' failure to learn from the past. AEH principles guide this study, and are used, together with insights generated from the study, as the basis for the design of AEH Guidelines.