Abstract This book offers a substantially new interpretation of what happened to slavery in Western Europe in the centuries that followed the fall of the Roman Empire. The periods at either end of the early middle ages are associated with iconic forms of unfreedom: Roman slavery at one end; at the other, the serfdom of the twelfth century and beyond, together with, in Southern Europe, a revitalized urban chattel slavery dealing chiefly in non-Christians. How and why this major change took place in the intervening period has been a long-standing puzzle. This book picks up the various threads linking the two ends of this transformation across the centuries, and situates them within the full context of what slavery and unfreedom were being used for in the early middle ages. These uses were very diverse and sometimes unexpected: early medieval people were extremely creative in their uses of the old Roman 'slave' category, and used it for purposes wholly different from those it was used for either before or after them. This book adopts a broad comparative perspective, covering different regions of Western Europe over six centuries, to try to answer the following questions: who might become enslaved, and why? What did this mean for them, and for their lords? What made people opt for certain ways of exploiting unfree labour over others in different times and places, and is it possible, underneath all this diversity, to identify some coherent trajectories of historical change?