This thesis demonstrates that friendship has particular relevance for postmodern ecclesiology and offers the basis for a relationally, rather than structurally conceived, understanding. It argues that friendship can be foundational for the Church community in contemporary times, as a means of self-understanding and as a basis for its mission. In doing this, it progressively explores friendship by means of an ongoing conversation with a variety of thinkers and theologians who have contributed to the subject. Each reveals, in a variety of disciplines, differing facets of friendship which ultimately contribute to a fresh understanding of ecclesial identity. This understanding shows the Church to be well placed to have friendship as its locus; in hospitality, a commitment to community, and the centrality of the Eucharistic meal. Friendship is shown to have a significant pedigree in philosophical thought, which has in turn influenced Christian theology. The thesis describes the paucity of incisive commentary on friendship in New Testament scholarship, and outlines the ambiguity surrounding friendship in postmodern culture, suggesting friendship's untapped potential as an ecclesial basis. Friendship's philosophical treatment in the classical era, particularly through Plato, Aristotle and Cicero provides a basis for its influence in Christian theology, as revealed by Augustine and Aquinas. The importance of friendship for personhood is explored through considering the nature of the self, specifically in conversation with Descartes and his challengers, particularly Nietzsche and Derrida. Applying this to the nature of the self in community, Bauman, Habermas, Derrida and Lyotard are amongst those who offer insights. This foundation allows a consideration of friendship as a particular instantiation of love, which sharpens the Christian principle of love for all people. From the insights of monasticism and Queer Theology, friendship's potential for a relationally rooted ecclesiology emerge: here the contribution of Aelred, Newman, Rudy and Stuart are significant. The Trinitarian theology of Zizioulas forms the basis for describing a communio ecclesiology, informed by Barth, Bonhoeffer, McFarland and Gunton, amongst others. This allows the Church as a community of friends, characterised by hospitality and centred on the Eucharist to be envisaged. The work of Derrida and Caputo on hospitality and 'the impossible' contribute useful insights into how this community might be resourced as it operates as the 'friends of Christ'.