This book is the first extended treatment of demand-rights, a class of rights apt to be considered rights par excellence. Centrally, to have a demand-right is to have the standing or authority to demand a particular action from another person, who has a correlative obligation to the right-holder. How are demand-rights possible? Linking its response to central themes and positions within rights theory, Rights and Demands argues for two main theses. First, joint commitment, in a sense that is explained, is a ground of demand-rights. Second, it may well be their only ground. The first thesis is developed with special reference to agreements and promises, generally understood to ground demand-rights. It argues that both of these phenomena are constituted by joint commitments, and that this is true of many other central social phenomena also. In relation to the second thesis it considers the possibility of demand-rights whose existence can be demonstrated by moral argument without appeal to any joint commitment, and the possibility of accruing demand-rights through the existence of a given legal system or other institution construed without any such appeal. The relevance of the book’s conclusions to our understanding of human rights is then explained. Classic and contemporary rights theorists whose work is discussed include Wesley Hohfeld, H. L. A. Hart, Joel Feinberg, Immanuel Kant, Thomas Scanlon, Judith Thomson, Joseph Raz, and Stephen Darwall.