The aim of this thesis is to consider the role of conservation in response to the theoretical and ethical challenges posed by contemporary art phenomena. This is pursued through the investigation of various theoretical conceptions of artwork ontology, of artwork and heritage identities, and of the ways in which these articulate the concept of ‘harm’ and the principle ‘dono- harm’ in conservation ethics. The thesis focuses on the harms that may be brought about to artworks by conservators by committing wrongs or injustices in decision-making processes due to the inadequacy of conservation’s conceptual frame for guiding decisions. The perceived complexity of emerging conservation challenges has led to a widespread recognition that traditional conservation ethics cannot be reconciled with the demands of contemporary art forms. Against this, it is argued that the conception of conservation as a system, and the suggested subsumption of key concepts defining the object of conservation and evaluating conservation practice under broader ones, provide an adequate conceptual frame. The new frame incorporates the particularities of both traditional and contemporary art phenomena, as a unified methodology for conservation decision-making.