This thesis deals with two themes in Catholic Social Teaching: the principle of gratuitousness and peacebuilding. The former is a relatively new articulation in Catholic Social Teaching that relies on the logic of the gift. The latter has and continues to be a global issue. The early scholarly discussion on gift-giving is widely traced to Marcel Mauss (1872-1950). He raised questions that drew the attention of philosophers and sociologists such as Jacques Derrida (1930-2004), Jean-Luc Marion (1946 - ), and René Girard (1923-2015). They advanced the discussion, highlighting opportunities and ambiguities. This thesis argues that Joseph Ratzinger/Benedict XVI writes about the logic of the gift in a positive perspective and situates it within Catholic Social Teaching. The dissertation maintains that rather than Catholic Social Teaching relying on the criteria of law and order guided by reason, the logic of the gift – which is based on the Christian notion of God, creation, the Trinity, and the human person – provides a resource for Catholic models of peacebuilding. It argues that this approach can supplement Basic Human Needs Theory– a significant model in the field of peacebuilding – that aligns with earlier Catholic social thought. The thesis concludes that Joseph Ratzinger/Benedict XVI’s writings on the subject can be a moral framework of encounter that supports theologically informed means to consider peacebuilding models and the practices of those who engage them.