This volume collects most of the author's publications on human action since the 1970s. The essays collected here are concerned to answer the questions ‘What makes us agents?’ and ‘What makes us responsible to one another for how we live our lives?’ The author develops a unified account of human agency and responsibility in terms of our capacity for critical evaluation, or normative competence. We are agents because we have (and to the extent that we exercise) this capacity, and we are responsible to each other for our lives as reflections of our exercise of this capacity. The account is developed in these essays largely by considering possible sources of normative incapacity, such as compulsion, addiction, manipulation, childhood deprivation, and one's own desires. Many of these essays engage critically with contemporary accounts of free will, action, and moral responsibility.