A preliminary framework for evaluating the effectiveness of international environmental agreements (IEAs) is described, and applied to the UN Plan of Action to Combat Desertification (PACD) and UN Convention to Combat Desertification (CCD), both of which have proven ineffective. There is good correspondence between the framework's nine criteria and official explanations of the reasons for poor implementation. Most of the criteria were identified in previous studies but opinions are divided on one of them—access to scientific knowledge. Its inclusion does, however, receive support from experiences in the desertification regime. Successive organizations of science-policy communication in the CCD have lacked many of the ideal features of boundary organizations, with access to scientific knowledge impeded mainly by formal institutions, compared with informal institutions in the PACD. Yet while applying the boundary organization model in a descriptive manner diagnoses the particular deficiencies in science-policy communication in this regime it cannot explain why they occur. Linking the CCD to a large and diverse scientific network, similar to the Intergovernmental Panel on Climate Change, could improve matters. But this may not be politically feasible, as new knowledge could undermine the viability of the CCD by unravelling its initial rule system. Progress in combating dryland degradation may therefore only be possible in another regime, e.g. in the successor to the Kyoto Protocol, or by devising a new interdisciplinary conceptualization of desertification which does not rely on ambiguity, as is the case at present. Copyright © 2009 John Wiley & Sons, Ltd.