Multiple artworks are works that can have multiple 'instances' which can play a particular kind of role in the appreciation of those works: for example, there can be multiple copies of a novel, or multiple performances of a musical work. An Ontology of Multiple Artworks is the first book-length critical analytic treatment of the metaphysical issues relating to 'multiple' artworks for over three decades. David Davies takes various considerations to which authors have appealed in arguing for ontological understandings of works in particular multiple art-forms as putative explananda, arguing that an adequate ontology of multiple artworks should be reflectively accountable to these. After clarifying what 'multiplicity' in the arts amounts to, Davies critically assesses the 'Platonist' idea that multiple artworks must be abstract or generic entities of some sort ('types') that exist independently of our creative and appreciative practices. The evolution of this idea is traced, and its ability to deal with the different explananda in play in the literature is gauged. The methodological constraints that should govern this kind of inquiry are also assessed. On the basis of these investigations, it is concluded that Platonism about multiple artworks is seriously compromised. Different non-Platonist options are then considered, and it is argued that the account that best explains the weighted explananda is the 'Wollheimian type' theory, according to which multiple artworks are performances essentially embedded in artistic practices. Finally, sceptical challenges to the very idea that there are such things as multiple artworks are considered.