The ESPGHAN-ESPID Evidence-based Guidelines for the Management of Acute Gastroenteritis in Children in Europe are the outcome of an important task that the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) has undertaken in collaboration with the European Society of Paediatric Infectious Diseases (ESPID). The collaboration was triggered by the understanding that acute gastroenteritis (AGE) is, still today and in all European countries, a major pediatric health problem. All children are expected to experience gastroenteritis in the first 3 years of age. Gastroenteritis is usually a mild disease in most European countries, but it is associated with a high number of hospital admissions and a not negligible number of deaths.