|Reference style||The Most Reverend|
|Spoken style||Your Excellency|
|Posthumous style||not applicable|
Josef Clemens was born on 20 June 1947 in Siegen in the Archdiocese of Paderborn). He received his secondary-level education in the Collegium Marianum in Neuss and studied theology at the Collegium Germanicum in Rome, where Cardinal Hermann Volk ordained him to the priesthood on 10 October 1975 in the church of Sant'Ignazio. After doing parish work in his home diocese, he returned to Rome to study in the moral theology faculty of the Gregorian University, obtaining a doctorate in 1983. In the following year he became personal secretary of Cardinal Joseph Ratzinger, the future Pope Benedict XVI, who was then Prefect of Congregation for the Doctrine of the Faith. He was given the rank of Chaplain of His Holiness on 17 March 1989.
On 12 February 2003, Pope John Paul II appointed Clemens Under-Secretary of the Congregation for Institutes of Consecrated Life and Societies of Apostolic Life. On 25 November of the same year, he was appointed Secretary of the Pontifical Council for the Laity and Titular Bishop of Segermes, receiving episcopal ordination on 6 January 2004 from Cardinal Ratzinger. As Secretary of the Pontifical Council for the Laity, he organized the 2005 World Youth Day in Cologne