John Leonardi founded the Company of Christian Doctrine, a group dedicated to teaching the catechism. He also founded the congregation of the Clerics Regular of the Mother of God (first called the Reformed Priests), which for a time was joined with the community of Saint Philip Neri.
He also served the Holy See as an inspector of religious orders, and together with Juan Bautista Vives he founded a school that later became the well-known Congregation for the Propagation of the Faith, dedicated to the Church’s mission work.
John died in Rome on October 9, 1609, after catching the plague while caring for the sick. His body rests in the church of Santa Maria in Campitelli. He was canonized in 1938.
