Until recently, deer hunting in medieval Scotland has been poorly researched archaeologically. In Hunting and Hunting Reserves in Medieval Scotland Gilbert identified medieval parks at Stirling and Kincardine in Perthshire that William the Lion created, but it is only in recent years that excavations by Hall and Malloy have begun to explore their archaeology. The Royal Commission on the Ancient and Historical Monuments of Scotland recorded another type of hunting feature, a deer trap at Hermitage Castle, in 1996 and then re-recorded the earthwork at Dormount Hope in 2000, originally reported as two separate monuments. Although the earthworks of parks and traps display similarities in the construction of their earthwork boundaries, the individual sites have variations in their topography that beg questions about their function. This paper establishes that the earthwork is indeed a single monument which has an open end allowing deer to be driven into the natural canyon of Dormount Hope. It goes on to discuss its dating in both archaeological and documentary terms and then its function as either a park, trap or hay (haga OE). This last possibility is raised by its apparent mention in a Melrose Abbey charter of the neighbouring estate of Raeshaw dating to the last quarter of the 12th century, made by the lords of Hownam, a family of Anglian origin. This Anglian connection leads to its interpretation as a hay – a kind of deer hunting enclosure or trap known in many parts of England prior to the Norman Conquest, for which ‘hay’ place names, such as Hawick, in the Scottish Borders provide support.