The goal of the International Drought Experiment (IDE) is to implement a highly coordinated, multi-site drought experiment requiring (in most cases) only a moderate investment of time and resources by investigators. This coordinated, distributed experiment will allow for the quantification of the impacts of four-year extreme drought across a wide range of terrestrial ecosystems based on a common experimental design and a comparable suite of measurements. The primary goals of IDE are to: (1) assess patterns of differential terrestrial ecosystem sensitivity to drought, and (2) identify potential mechanisms underlying those patterns. IDE will significantly expand the scope of past drought experiments by including as broad a range of ecosystem types as possible, ensuring that these experiments are accessible to as many investigators as possible, and overcoming the limitations of past drought experiments (i.e., lack of coordination, differences in approaches and methodologies, etc.).