This collection of papers examines water management in two of the world's prominent, arid transboundary areas facing similar challenges. In the Middle East, the chronically water-short Israeli-Palestinian region has recognized the need both to conserve and supplement its traditional water sources. Across the globe on the North American continent, Arizona-a state in the southwestern United States bordering Mexico-relies significantly on the overallocated Colorado River, as well as on non-renewable groundwater supplies. For both regions, sustainable and cost-effective solutions clearly require innovative, multifaceted, and conflict-avoiding approaches. This volume is predicated on the role that "science diplomacy" can play in resolving difficult water-related issues. The history of natural-resources disputes confirms that the scientific approach can reveal ways to overcome division. Experience has shown that scientifically-trained experts who are sensitive to sociopolitical conditions can assist in developing and evaluating feasible water management solutions. The insights and expertise of a distinguished and diverse group of researchers fill these chapters. Contributors include established authorities as well as a number of budding scholars. In a field traditionally dominated by males and by engineers, this collection benefits from significant gender diversity and contributions from a broad spectrum of disciplines. Policymakers, water managers, specialists such as university researchers and consultants, and citizens all have an interest in finding sustainable strategies to address the many water-management issues discussed in this volume. The assembled papers underscore that much work remains to be done.