This paper uses the method of process tracing in order to follow how the change in the Vatican leadership on the year of 1978 contributed to the shift in its foreign policy towards an anti-communism policy that helped on the fall of the Polish communist regime. In the late 1970s, the Vatican influenced the political change on some Communist countries. The final years of the Cold War introduced a range of new actors that contributed to the American preponderance in the international system after the demise of the USSR. Among them, we can highlight the rebirth of the oldest diplomacy in the world, which was able to be among the high players in the system once again: the Holy See. Also, the cooperation between the American president Ronald Reagan and Pope John Paul II is a controversial point that must be investigated. It is possible to assert, however, that Karol Wojtyła played an essential role during the Polish political transition and that it was possible because of the partnership that His Holiness developed with Ronald Reagan
