The issue of the conventionality of geometry is considered in the light of the special theory of relativity. The consequences of Minkowski's insights into the ontology of special relativity are elaborated. Several logically distinct senses of “conventionalism” and “realism” are distinguished, and it is argued that the special theory vindicates some of these possible positions but not others. The significance of the usual distinction between relativity and conventionality is discussed. Finally, it is argued that even though the spatial metric within an inertial reference frame is euclidean, it is impossible to define unique objects which can serve as the relativistic surrogates of the spatial points of classical geometry.