How is one 'authentically' modern? Substantively drawing on contemporary social theory, this book investigates the multiplicity of answers that Muslims have given to this question since the end of the nineteenth century. Through six historical and thematic case studies, the chapters examine the historical evolution of multiple modernities within Islam. The book argues that we can observe the rise and spread of a relatively hegemonic idea according to which a relation to Islamic traditions bestows projects of Muslim modernities with cultural authenticity. At the same time, the book provides an interpretation of this specifically Islamic discourse of modernity as an inherent part of global modernity in conceptual terms understood as the emergence of world society.