In this thesis I focus on Wallace's understanding of ethical agency: how it is constituted, how it manifests or fails, and the nature of its contingencies and limits. To this end, I explore ideas of ethics and freedom throughout Wallace's oeuvre from four broad theoretical perspectives. Beginning with a study of Emmanuel Levinas's 'Ethics as First Philosophy', I compare Wallace's and Levinas's writings on ethics to the theories of Jacques Derrida, Maurice Blanchot, and Slavoj Žižek. I investigate Levinas's use of the face or the face-to-face encounter as an ethical signifier and read Wallace's own rich depiction of faces through this lens. In the second chapter I depart from postmodern theory and deploy concepts from clinical and biomedical science to re-evaluate Wallace's writings on free will and agency in light of the 'neuroethical'. I show how Wallace's attention to the materiality of the body and the brain disrupts simple notions of an ethical agency founded on free will and personal choice. This leads to the third chapter's consideration of how Wallace positions the biopolitical subject under neoliberal social and cultural frameworks, including his interrogation of mythologies around competition and work in contemporary America. Finally, in the fourth and final chapter I analyse Wallace's oeuvre from the viewpoint of feminist theory, drawing a comparison to Julia Kristeva's writings on heretical ethics and the abject. I discuss the problem of misogyny in Wallace's texts and evaluate more recent criticism that reconsiders his collected writings in light of rapidly changing categories of sex and gender.