Sustainable development is defined as development that meets the need of the present without compromising the ability of future generations to meet their own needs. Sustainability requires conservation of resources, minimizing depletion of nonrenewable resources, and using sustainable practices for managing renewable resources. Water is truly at the core of sustainable development. It is inextricably linked to climate change, agriculture, food security, health, equality, gender, and education, and there is already international agreement that water and sanitation are essential to the achievement of many sustainable development goals. This chapter provides a general overview of sustainability concepts that can be applied to water resource management. Chapter topics include an historical perspective on sustainability issues, the topic of resource limitations, sustainable development considerations, ways to benchmark sustainability, resources to support moves toward sustainability, and future trends in sustainable development and assessment. An application section provides five Illustrative Examples exploring sustainability concepts.