For many decades, Buddhism in the West has been conceived as an ‘other-worldly’ religion with very little or –at least—limited authority in the public arena. This partial view of the Buddhist path overlooks the potential of Buddhism to interpret reality and help establish new causes and conditions to improve it. This thesis is rooted in Buddhism and seeks to develop a Buddhist theology in order to understand how international relations, as part of the contingent reality, are subject to change. Thus there is the possibility of reconstructing reality through the sum of individual will expressed in social groups, institutions and states. This Theology of International Relations follows a methodology of causality rooted in the dependent origination found in Buddhist theology. Thus, relative reality is conceived as the result of the interaction of different causes and conditions; individuals, through their thoughts and actions, provide new conditions which will be crystallized in particular social arrangements through an inter-subjective consensus. This arrangement is highly influenced by the individual’s allegiance with the sacred, however this is conceived, and thus establishes an ethical guideline in the individual’s relationship with other sentient beings and the ultimate level of existence. This dependent construction of reality goes from the individual level of analysis to the social, state, interstate and global levels in a chain of contingent reality. Therefore I suggest that states, institutions and society are the reflection of shared ideas, beliefs, goals and perceptions of reality between individuals. The human capacity to shape reality is rooted in the premise that they face a relative reality, one that is contingent on several causes and conditions. In Buddhism, all sentient beings play a key role in shaping reality but human beings play a unique role because they can overcome suffering when they recognize the interdependent relation of causes and conditions in a relative reality. If this is achieved, then absolute reality can be experienced, wherein the individual goes beyond all conceptions and senses in a state of emptiness of the self. These core ideas of a contingent reality, its construction through an inter-subjective consensus and the need to experience an absolute reality are premises which Buddhist theology developed and which this thesis explores. In chapter one this thesis considers the basis of Buddhist theology and how it explains the experience of the sacred, the role of religion and the potential for the construction of a relative reality. This thesis argues that religion is at the core of human existence as a vessel of faith which follows a particular theological path toward a communion with the divine. The Buddhist path, aware of the interaction of different levels of reality—relative and absolute—also conceives inner development and social change as key elements of an interdependent transformation. The idea of ‘world peace through inner peace’ is one advocated by ‘engaged Buddhists’ and found in the ethical code of Buddha’s message. Chapter two examines how international relations became the arena where individuals, institutions and states converge and reflect the basic premises of their world-views, whether rooted in anger, hatred and ignorance of the interdependent nature of all phenomena, or based in compassion and awareness of a shared common good. In addition, it addresses the issue of the resurgence of religion in international relations and how it is present or absent from political science theories and policy making. Through this analysis, several established elements such as the concept of the state, secularism and religion as a source of war, are challenged in a new era of multi-agency and mutual influence through religious ideas, groups and communities. Following this inter-subjective construction of the world, the thesis presents two case studies which argue that religious leaders exercise political influence through their actions, ideas and beliefs. The first is the life and works of Tenzin Gyatso, the Fourteenth Dalai Lama in chapter three and the second is the life of Archbishop Desmond Tutu in chapter four. The former having suffered the violent occupation of Tibet and the continuous attacks on Tibetan culture that led him into exile, and the latter having faced the policies of hatred under apartheid, the Dalai Lama and Tutu managed to suggest a world where forgiveness is rooted in compassion and were human beings share the responsibility of creating a compassionate reality. The final chapter develops a new approach to the study of religion and politics providing new variables of study and new categories to understand how international relations are influenced by religious ideas and movements. This thesis argues that there is a need to study and understand this interdependent relation between religious and secular actors through theoretical approaches in international relations and opens the discipline to new paradigms such as the Buddhist theological approach. The outcome of this partnership depends on the individual’s decision to engage, whether in negative causation that leads to violence, fear, terror and the perpetuation of suffering or in a positive one which opens the possibility of peace and liberation from suffering through compassion, forgiveness and reconciliation, recognizing our common humanity and shared universal responsibility.