More than five years of war have pushed millions of Yemenis into increasingly desperate coping mechanisms. Conflict, spread of diseases, economic crisis, and the breakdown of institutions are driving high levels of humanitarian need. Conflict between the internationally recognised Government of Yemen (GoY) and the Houthi movement escalated following the Houthi takeover of the capital, Sana’a, and the consequent intervention of the Saudi-led coalition in support of the government in March 2015. Since then, the conflict has resulted in over 100,000 casualties, displacement, severe access constraints, and an economic downturn affecting food and fuel, leaving approximately 24.3 million people (80 per cent of the population) in need of humanitarian assistance. These four scenarios are not attempts to predict the future. Rather, they describe situations that could occur in the coming six months and are designed to highlight the possible impacts and humanitarian consequences associated with each scenario.