Modern slavery is a major topic of concern in international law and global governance, in civil society, and in academic debates. Yet, what does modern slavery mean, and can its highly different forms be covered in a single concept? This paper discusses these questions in three steps: First, it develops common definitions of modern slavery. Second, it discusses critical rejections of these definitions. The two camps that adhere to the definitions of modern slavery, and that reject them, respectively, face certain (...) limits. In a third step, the paper takes up with the limits and the strengths of both. It suggests that the limits of definitions of modern slavery can be overcome by critical approaches; and that the limits of critical approaches can be overcome by definitions of modern slavery. The key is their integration into a human rights frame. Ultimately, the paper proposes an approach to modern slavery that neither relies on a binary distinction between slavery and non-slavery, nor does it strive for the abolishment of the concept of modern slavery. Rather, the paper calls for a normatively and contextually embedded approach within the human rights frame. (shrink)