This dissertation advances a critical appropriation of Thomas Aquinas's thought on the virtue of humility. Humility has received relatively little scholarly attention since early modernity, and the attention it has received has been largely negative, due to humility's association with religiously inspired attitudes that diminish the human drive for excellence. In recent decades a small number of philosophical and religious ethicists and political theorists have argued that humility, properly understood, is indeed a virtue. However, these accounts have not paid sufficient attention to the way various forms of oppression force a shift in thinking about what humility is and why it is of value. Feminist thought illuminates the social and psychological dynamics of oppression, but it has almost completely ignored the topic of humility. Where humility has been discussed by feminists, it has generally been dismissed as supportive of patriarchy and thus destructive of women's well-being. Humanity is in need of a new account of humility that answers to important criticisms. This dissertation offers such an account by critically appropriating Aquinas's thought on humility. It argues that humility is crucial to the realization of relational selfhood, and it definitely promotes the common good, but only if its operations are coordinated with the exercise of courage and justice.