Land-surface modeling has shown rapid development in the past two decades. Where energy and water fluxes were the primary focus of studies in the late 1980s and early 1990s, increasing attention to the global carbon cycle triggered the development of models addressing vegetation phenology, dynamic vegetation structure, and carbon pools. In the meantime, improved representations of wetlands, urban areas, interactions between irrigation and ground water, nutrient cycles, cryosphere processes and land properties, and in particular, spectral intervals to enable satellite data assimilation, have continued to be developed. This expanding scope is driven by the growth of interdisciplinary studies of the Earth system. The Global Land/Atmosphere System Study (GLASS) encourages these developments by coordinating the evaluation and intercomparison of the new generation of Land Surface Schemes (LSSs) and their applications to scientific queries of broad interest. Thus, a key objective of GLASS is model development and evaluation. In addition, because the land-surface component does not stand on its own and is tightly coupled to the atmosphere in many ways, GLASS projects also address these aspects on both local and global scales.