Orthodox theologians such as Bulgakov, Florovsky, Afanasiev, Staniloae, and Zizioulas consider eucharistic communion to be the sign of ecclesial unity, but their understandings of the boundaries of the church and unity in love, teaching, episcopacy, and Eucharist (including intercommunion) are varied. This chapter analyses Orthodox understandings of the relationship between the Orthodox Church and the Una Sancta of the creed, considers the ecclesial status of other Christians, and assesses various models of unity, such as ‘all in each place’ (New Delhi, 1961). Unity is conditioned theologically: Christians need to confess the same faith, though uniformity is not the goal. Churches should enjoy unity in love, common service at the altar of the poor (in ‘the liturgy after the liturgy’), synodal decision-making, and communion among local churches represented by their bishops. These forms of unity do not represent successive stages, but they mutually condition each other.