Stefan Döring’s dissertation examines the consequences of water scarcity in innovative ways, using data from Africa, the Southern Mediterranean, and parts of the Middle East. As a unique and vital resource, water has been a target for peace research across disciplinary boundaries over several decades. Döring’s four essays push this research forward in many important ways. In the first essay, Döring employs subnational data on groundwater access from Africa and the Middle East and demonstrates that poor access to groundwater increases the risk of communal violence. In the second essay, with Katariina Mustasilta, Döring analyzes spatial spillover of communal conflict. Using subnational data from Sub-Saharan Africa and advanced spatial modeling, the essay shows that drought, although not linked to conflict locally, can cause conflict in nearby areas through spillover processes. The two last essays shift the focus to cooperation. In the first one of these – the first large-N study of water cooperation at the sub-national level – Döring demonstrates that water cooperation occurs in areas with poor access to groundwater, even in places with a history of violence. In the final essay, the unit of analysis shifts to the individual level. Döring and Jonathan Hall draw on survey experiment data collected among refugees from Syria and Iraq and show that respondents who have faced drought earlier in life show substantially lower levels of altruism toward individuals belonging to other ethnoreligious groups than their own. The findings reported in this book make significant contributions to our understanding of sustainable water management and environmental peacebuilding. In particular, scholars interested in how water resources affect cooperation and conflict among non-state actors will find this book invaluable.