In what ways has language been central to constructing, challenging and reconfiguring social and political boundaries? This volume traverses space and time to explore the construction of such boundaries. Focusing on the ways that language functions as an inclusive and divisive marker of identity, the volume includes case studies on Scandinavia, the Netherlands, Belgium and Luxembourg. It also explores the northern and southern borderlands of present-day Germany as well as the city of Cologne and the surrounding Ruhr area. The chapters critically engage with focused accounts of past and present language situations, practices and policies. Taken as a whole, the volume stresses the importance of studying metalinguistic perspectives as a means of enabling detailed analyses and challenging generalizations.