The need for improved horizontal knowledge management at the national and international levels is essential for monitoring and assessment of land degradation and desertification. At the national level, governments utilise scientific, socio-economic and technical data and information for strategic planning, priority setting and national environment and development planning. However, challenges including the lack of capacity and lack of collaboration and sharing of information across governments affect responses to and the effectiveness of monitoring and knowledge exchange, along with the ability to effectively implement treaties. At the international level, a number of Multilateral Environmental Agreements (MEAs) share cross-sectoral themes related to research and monitoring, information exchange, technology transfer, capacity building and financial resources. The need for increased synergies stems from the similarities between the issues they address. Challenges for improving knowledge management at the international level include insufficient interaction between the scientific bodies of the various MEAs; duplication of reporting, monitoring and assessment efforts; limited knowledge management between the various assessments addressing ecosystems and biological diversity during the past decade; and insufficient collaboration between the United Nations Convention to Combat Desertification (UNCCD), the UN system and the international non-governmental organisation (NGO) community. This paper examines these challenges and offers recommendations on how monitoring and assessment knowledge can be better managed at the national and international levels. Copyright © 2011 John Wiley & Sons, Ltd.