Quantitative data on dryland changes and their effects on the people living there are required to support policymaking and environmental management at all scales. Data are regularly acquired by international, national or local entities, but presently exhibit specific gaps. Promoting sustainable development in drylands necessitates a much stronger integration, coordination and synthesis of available information. Space-based remote sensing systems continue to play an important role but do not fulfill all needs. Dedicated networks and observing systems, operating over a wide range of scales and resolutions, are needed to address the key issues that concern decision-makers at the scale of local communities, countries and the international community. This requires a mixture of ‘bottom–up’ and ‘top–down’ design principles, and multiple ownership of the resultant system. This paper reviews the limitations of current observing systems and suggests establishing a Global Drylands Observing System, which would capitalize on the achievements of systems already established to support the other Rio Conventions. This Global Drylands Observing System would provide an integrated, coherent entry point and user interface to a range of underlying information systems, identify and help generate missing information, propose a set of standards for the acquisition, archiving and distribution of data where these are lacking, evaluate the quality and reliability of these data and promote scientific research in these fields by improving access to data. The paper outlines the principles and main objectives of a Global Drylands Observing System and calls for renewed efforts to invigorate cooperation mechanisms between the many global environmental conventions.