Changing Origins and Trade Routes of Scottish Window Glass Helen M. Spencer Abstract Window glass used in Scottish medieval ecclesiastic and monastic buildings was not made in Scotland. Instead, all glass was imported but there is limited evidence as to where this window glass was made. In this chapter, archaeological and archival evidence for window glass in the twelfth-fifteenth centuries in Scotland has been re-examined and previous work to chemically characterise glass compositions from these regions is summarised. The largest programme of chemical characterization of late medieval window glass yet carried out in Scotland was undertaken to provenance the location of manufacture of the window glass used in a range of buildings.