While there is growing appreciation for our soil re sources and the need to as sure sustain ability in their management, we do not as yet fully understand where, when, and how soil degradation affects food security; how important this problem is relative to other constraints in developing countries; and what policy and other actions to take to mitigate adverse effects of soil degradation. Until relatively recently, there has been a dearth of research on this topic, leading to uninformed dialogues and debates and leaving policymakers some what at a loss about whether and what to do to address soil degradation threats to food security. In this comprehensive paper, Sara J. Scherr lucidly explains why and when soil degradation should be of particular concern to policymakers interested in assuring food security. She reviews over 80 recent studies to assess the past and present food-security related effects of soil degradation, and, on the basis of this evidence and assessments of the likely future trends in agricultural land use, she predicts future patterns of soil degradation and the threats they pose to food security in the developing world by 2020. Scherr convincingly argues that soil degradation does not have to threaten food security in developing countries and provides guidance on policy and research priorities to reduce these threats in each of the major pathways of agricultural land use in developing countries.