This volume offers a critical appraisal of the theology of John Zizioulas, acclaimed advocate of ecumenism. Leading Anglican, Reformed, Catholic and Orthodox international scholars, including Colin Gunton, Nicholas Loudovikos, Paul McPartlan, Wolfhart Pannenberg and Philip Rosato present essays which analyse Zizioulas' trinitarian doctrine of God, and his theological account of the Church as the place in which freedom and communion are actualised. Many include discussions of Zizioulas' Being as Communion as well as other lesser known works, now available in Communion and Otherness. Together they represent an unrivalled introduction to the work of this great theologian.