Emergency departments are the front line of health care systems and play a critical role in ensuring an efficient and high-quality response for patients in stress or crisis situations. A growing demand for emergency care might however reduce patients’ satisfaction (through waiting times), increase health provider workload and adversely affect quality of care. This working paper begins with an overview of the trends in the volume of emergency department visits across 21 OECD countries. It then explores the main drivers of emergency department visits in hospital settings, paying attention to both demand and supply side determinants. Thereafter, national approaches instituted by countries to reduce the demand for emergency care and to guarantee a more efficient use of emergency resources are presented.