The Sustainability and Organic Livestock model (SOL-m) is a project (see Concept Note) of the FAO Natural Resources and Management Department that has been commissioned to the Research Institute of Organic Farming (FiBL) in Frick, Switzerland. This summary report presents the preliminary results of the SOL-model. Currently, plausibility checks are conducted, model parts are refined and further data is gathered for verifying the trends specified thus far. The full project outcomes and a dedicated publication, including quantitative impacts of the scenarios, will be availble in mid June 2013. The outcomes of the current Phase I of SOL-m point to substantial environmental, social and economic potential of a global conversion to grassland-based farming. Thus, FAO has already engaged in Phase II of SOL-m on Sustainable Grasslands.