Natural disasters such as cyclones, droughts, earthquakes, floods, landslides, volcanoes, or pandemics routinely have cross-border implications. Transboundary risks of natural disasters tend to be the greatest for neighboring countries but often extend regionally or even globally. Even disasters with seemingly localized impacts contained within the national borders of a given state may have indirect short-term or long-term effects on other countries through refugee flows, conflict spillovers, volatility of global commodity prices, disruption of trade relations, financial flows, or global supply chains. Natural disasters may increase the risk of interstate conflict because of commitment problems, reduced opportunity costs of conflict, shocks to status quo divisions of resources, or demarcation of territories among countries, or because of leaders’ heightened diversionary incentives in favor of conflict. In some cases, disasters may have a pacifying effect on ongoing hostilities by creating opportunities for disaster diplomacy among conflict parties. Population displacement in disaster zones can send refugee flows and other types of migration across borders, with varying short-term and long-term socioeconomic and political effects in home and host countries. Adverse effects of natural disasters on regional and global economic activity shape patterns of international trade and financial flows among countries. To mitigate such risks from natural disasters and facilitate adjustment and recovery efforts, countries may turn to international cooperation through mechanisms for disaster relief and preparedness. Regional and global governmental and non-governmental organizations (NGOs) are common means to initiate and maintain such cooperative efforts.