Human dignity: social movements invoke it, several national constitutions enshrine it, and it features prominently in international human rights documents. But what is it, why is it important, and what is its relationship to human rights and social justice? Pablo Gilabert offers a systematic defense of the view that human dignity is the moral heart of justice. In Human Dignity and Human Rights (OUP 2019), he advanced an account of human dignity for the context of human rights discourse, which covers the most urgent, basic claims of dignity. This book extends the dignitarian approach to more ambitious claims of maximal dignity of the kind encoded in democratic socialist conceptions of social justice. In particular, this book focuses on the just organization of working practices. It recasts in a dignitarian format the critique of capitalist society as involving exploitation, alienation, and domination of workers, and revamps a neglected but inspiring socialist principle. In its dignitarian interpretation, the Abilities/Needs Principle ("From each according to their ability, to each according to their needs!") yields reasonable and feasible requirements on social cooperation so that it solidaristically empowers each human being to lead a flourishing life. While Human Dignity and Human Rights offered the first systematic account of human dignity in human rights discourse, Human Dignity and Social Justice presents the first systematic application of the dignitarian framework to the core ideals of democratic socialism.