Children under five experience 1.7 billion episodes of diarrhea each year, resulting in 36 million cases of severe disease and 700,000 deaths, or 10% of all child deaths worldwide. As the severity of diarrheal disease can vary quite widely in children, accurately assessing dehydration status remains a crucial step in preventing morbidity and mortality. While children with severe dehydration require immediate treatment with intravenous fluids to prevent hemodynamic compromise, organ ischemia, and death, children with mild to moderate dehydration have a significant reduction in hospital length of stay and fewer adverse events when treated with relatively inexpensive oral rehydration solution (ORS). The World Health Organization (WHO), the US Centers for Disease Control and Prevention (CDC), and the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) recommend separating children with acute diarrhea into three groups to determine management based on the presence or absence of various clinical signs: no dehydration (<3%), some dehydration (3-9%), and severe dehydration (>9%). These authorities recommend treating children with some dehydration with ORS and limiting IV hydration to children with severe dehydration, in order to prevent the inappropriate utilization of scarce hospital resources and the adverse events associated with a more liberal use of IV hydration in children. However, no clinical prediction model for severe dehydration has ever been empirically derived and validated in a developing world setting, where the vast majority of diarrheal deaths occur in children each year.