The Konza Prairie LTER Program is a comprehensive, interdisciplinary research program designed to provide an understanding of ecological processes in mesic grasslands, particularly tallgrass prairie, and contribute to conceptual and theoretical advances in the field of ecology. The Konza Prairie LTER program also offers educational and training opportunities for students at all levels, contributes knowledge to address land-use and management issues in grasslands, and provides infrastructure and data in support of scientific pursuits across a broad range of disciplines. Konza was one of 6 original LTER sites, and pre-LTER research extends selected datasets back >28 years. The focal site for our core LTER research is the Konza Prairie Biological Station, a 3487-ha area of native tallgrass prairie in the Flint Hills of northeastern Kansas. The KPBS was established in 1971, with land acquired by the Nature Conservancy and deeded to Kansas State University, and the site became a part of the LTER Network in 1981. The Konza LTER program encompasses studies at, and across, multiple ecological levels and a variety of spatial and temporal scales. The unifying conceptual framework guiding this research has been that fire, grazing and climatic variability are essential and interactive factors shaping the structure and function of mesic grassland ecosystems. The interplay of these natural disturbances across a heterogeneous landscape leads to the high species diversity and complex, non-linear behavior characteristic of these grassland ecosystems. Because grazing and fire regimes are managed in grasslands worldwide, Konza LTER data are relevant not only for understanding this and other grasslands, but also for addressing broader ecological issues such as productivity-diversity relationships, disturbance and community stability, top down vs. bottom up controls of ecological processes, and the interplay of mutualistic and antagonistic biotic interactions. In addition, because human activities are directly (management of grazing and fire) and indirectly (changes in atmospheric chemistry and climate) altering the key drivers of ecological processes in these grasslands we are poised to use Konza LTER studies and data to address critical issues related to global change, including the ecology of invasions, land-use and land-cover change, human activities and water quality, and ecosystem responses to climate change. Thus, this long-term research program initiated >20 years ago to understand the effects of natural disturbances in this grassland, now has additional and immediate relevance for understanding and predicting the consequences of global change taking place in the grasslands of North America, and around the world. The Konza LTER program continues to build upon a long-term database on ecological patterns and processes derived from a fully replicated watershed-level experimental design, in place since 1977. This unique experimental design includes replicate watersheds subject to different fire and grazing treatments, as well as a number of long-term plot-level experiments which allow us to address the mechanisms underlying responses to various fire and grazing regimes. The effects of climate are being addressed by long-term studies encompassing the natural climatic variability, and possible directional changes, characteristic of this region, as well as manipulations of water availability and temperature in ongoing field experiments (i.e., the Irrigation Transect Study and the Rainfall Manipulation Plots (RaMPs Experiment). Within core LTER watersheds, permanent sampling transects are replicated at various topographic positions (n=4/topo. position/watershed), where ANPP, plant species composition, plant and consumer populations, soil properties, and key above- and belowground processes are measured. The collection of diverse data from common sampling locations facilitates integration among our research groups. In total, the Konza LTER Program incorporates explicit study of the major factors influencing mesic grasslands in a long-term experimental setting. It is a rigorous ecological research program designed to elucidate patterns and processes inherently important in grasslands, and address the potential impacts of global change in these ecosystems. Towards this end, we currently maintain >70 long-term datasets in association with long-term experiments ongoing as part of this program, and many more research activities of planned shorter duration.