This article approaches the problematic of relationships between the World Council of Churches (WCC) and Pentecostalism, mainly from the perspective of membership of Pentecostal churches in the WCC. It contents a brief presentation of some prejudices regarding Pentecostals in the ecumenical movement and a historical survey of the relationships between the WCC and Pentecostals, as well as a more detailed analysis of the actual status of this relationship from the perspective of membership of Pentecostal churches in the WCC. The last section assesses possible future scenarios in this regard. It is underlined that the Pentecostal movement is already represented in the WCC by a few small Pentecostal churches and that all the debate on whether to accept new Pentecostal member churches in this ecumenical organization should have as its starting point the reality that Pentecostalism is already part of the WCC. After presenting in detail the last debate in the Permanent Committee on Consensus and Collaboration (PCCC) on the issue of the WCC opening the doors to Pentecostal churches, this article concludes that the WCC should follow its previous policy of analyzing individually each application for membership according to its criteria for accepting new members. While most Pentecostal churches would agree with the basis of the WCC and some might increase their ecumenical engagement at all levels, in the near future at least, Pentecostal churches may still have a long way to go to integrate themselves in a genuine ethos and desire for unity.