Although the much-postponed subject of papal primacy in the ecumenical dialogue between the Catholic and the Orthodox Churches finally got to a formal start in 2007, it was set in a wider framework of synodality or conciliarity. Thus the Roman primacy is theologically twinned with the ecumenical councils. In this context the article draws attention to the Council in Trullo (692). Neglected in the post-Tridentine West, in the East it had long been regarded as an ecumenical council. This council is of interest not only for canon law but for theology, liturgy, sacred art, and church history as well.