This Report examines the urgent global challenge of sustainable development, and its relationship to rising inequality within and among countries. It strives to identify polices that would make development both more sustainable and more equitable. The integral relationship between inequality and unsustainability is recognized. The inequitably apportioned control and consumption of natural resources is a key driver of global warming — and yet those who will suffer most from climate change are disproportionately those least responsible for environmental deterioration. The Report seeks to identify ways in which sustainability and equity can be jointly advanced. It examines long-term trends in inequality at national and global levels, and argues why it is essential to promote practices today that will both increase sustainability and reduce inequality for future generations.