Since Vatican II was convened as an ecumenical council, most Orthodox autocephalous churches initially refused to send observers without full voting rights. For non-theological reasons, Russia was the exception that sent observers to the first session. Other Orthodox churches followed suit at later sessions. Despite their inability to vote or speak at plenaries, Orthodox delegates contributed to the Council’s documents, ecumenical openness, attitude towards communism, and from a humanitarian perspective. By granting Orthodox observers a prominent role, Vatican II represents a model of ecumenical integration in the conciliar process.