The 10th plenary assembly of the International Commission for Theological Dialogue between the Catholic and Orthodox Churches began today.
After a Tuesday event open to the public, the theologians will work behind closed doors through Sunday.
The commission was formed in 1980. Differences brought the group to a halt for six years, but the members resumed discussions at the end of 2005.
The panel is led by co-presidents: Cardinal Walter Kasper, president of the Pontifical Council for Promoting Christian Unity, and Metropolitan Ioannis Zizioulas of Pergamo.