The papers in this collection are concerned with certain foundational aspects of quantum gravity. We have chosen to group them together under the banner of ‘structuralism’. The ways in which the various papers fall under this banner, and the extent to which they do so, are somewhat diverse. Cao, for example views quantum gravity as lending support to a structural realist conception of ontology. Stachel likewise advocates a similar view, though the two authors’ views are very dissimilar in their details. Dorato and Pauri’s contribution, an attempt to motivate a position they call ‘structural spacetime realism’, bears many similarities to Stachel’s position, though they steer clear of the relationalist label that Stachel is happy to wear. Pooley, on the other hand, cautions against the pulling of structural realist views from the formalism (specifically from diffeomorphism invariance). Instead he argues that there is a perfectly reasonable and preferable non-structural interpretation that can be given; namely, ‘sophisticated substantivalism’. Interestingly, both Stachel and Pooley see the developments of quantum gravity (or diffeomorphism-invariant physics in general) as working against the view known as ‘haecceitism’—namely the view that there can be possibilities that differ non-qualitatively (solely in virtue of which objects play which role in the qualitative structure). Stachel interprets this as motivating a relationalist position according to which objects, insofar as they exist at all, are simply conceived as deriving their existence from their place in a network of relations. Such a position gives a structural characterization of objects.