The Board of Deputies has approved the membership of Yachad, the campaign group which lobbies for a two-state solution to the Israeli-Palestinian conflict.
Such was the controversy surrounding the application that a decision had twice been previously postponed.
While many had anticipated that the group might struggle to obtain the necessary two-thirds majority, deputies voted by 135 by 61 on Sunday to accept Yachad.
In a half-hour debate, most of the speakers supported its application, though a number stressed that they did not agree with the policies of the group but regarded its membership as a matter of democracy.