The article examines the meaning of the common priesthood of Christians from the perspective of the ecclesiology of the People of God in communion, developed during the Second Vatican Council. It studies the biblical and patristic foundations of the common priesthood while understanding its originality in relation to the Old Testament priesthood. It looks at the priesthood of Christ as the foundation for understanding the common priesthood of Christians. It digs into total ecclesiology and relates the unity and specifi city of the priestly, prophetic and kingly mission of Christians as a priestly people. It highlights the meaning of the word common defi ned by the Vatican Council to designate the priesthood of the baptized. It distinguishes the specifi city of the ordained ministry s priestly exercise from that of laity while emphasizing the sense of the action of the lay people in the world. It emphasizes that the ecclesial identity of the lay Christian is not to be established as the noncleric. Although the common priesthood is not exclusive to the lay Christian faithful, not knowing how the laity sanctify their daily lives and how they exercise their baptismal priesthood also undermines the development of the Church’s pastoral and evangelizing action.