<p>Some theorists have argued that novel food objects spur ontological debates and are thus grounds for the disruption of problematic normative ontologies. In this paper, I take up this claim to consider how disputes about milk and alternatives, among them synthetic milk, manifest certain ontological commitments. Through a political approach to ontology, I argue that the disruption of hegemonic ontologies can afford novel ethical considerations otherwise concealed from view. Drawing on ecofeminist critique of dairy, and feminist critiques of biocapitalism, I show how debates about milk and alternatives reinscribe an ontology of living and natural bodies as resources for the accretion of capital, and the way that ontologies of sex, gender and nature function within these debates. I argue that the actual materiality of milk is concealed through industrial processes, as well as public discourse. I then offer an alternative materialist ontology of milk, on the basis that an emphasis on the materiality of mammalian milks, including human, can unveil ethical considerations otherwise concealed in conceptual debates about milk; I articulate this materiality as a relational materialist ontology, building on existing distinctions between substance and relational ontologies of food. I argue that the effect of this commitment to materiality is the provision is to counter a principalist approach to the ethics of milk by taking milk’s materiality as a paradigm for reflecting on the necessity of situatedness for any such ethics.</p>