The present participation of the Catholic Church int he modern ecumenical movement is very diffrenet from what it was at its beginning. The Church gradually, from an attitude of opposition and rejection, shifted to acceptance, participation, and finally to absolute preoccupation with the ecumenical movement. The turning point was marked by the Second Vatican Council which, from its convening to the intonation oft he Council documents and the implementation of their guidelines in the life od the Church, showed that the ecumenical path is the path the Curch is called to follow if she wants to fulfull the mission she received from the Lord. So it isn't wrong to say that the ecumenical efforts oft he Catholic Curch regarding the ecumenical movement can be divided into the time before the Council and the time after the Council. This paper follows that chronology. The first part shows the cange of mentailty within the Curch, with an emphasis on the fruits od the Second Vatican Council and the pontiffs oft he post-council popes. The second part focuses on the bishop's role in ecumenism, which is highlighted in major post-council church documents. The emphasis is on the latest document oft he Pontifical Council for Promoting Christian Unity – Bishop and Christian Unity: Ecumenical Vademecum, issued on December 4, 2020.