What are human rights? Why do we have them? How do we know for sure which rights are specific to humans? And how should we respond when we disagree on them and on the obligations we owe to others who claim human rights? These are just a few of the questions taken up in this broad-ranging and systematic introduction to the theory of human rights. The author draws on both traditional perspectives and current debates in the field to address key contemporary issues and conceptual questions. She asks whether or not human rights can be said to be universal, and whether human rights can encompass global justice, environmental rights and global security for future generations. In addition she explores the particular effects of differences of gender, sexuality, culture and religion on the nature of human rights in contemporary society, and the implications these might have for international legal and political regimes. Providing a comprehensive and accessible account of the key theoretical ideas in the field, this text is essential for those seeking to understand the importance of human rights in shaping the moral and political claims of individuals, cultures and societies across the world.