The 120 oldest papal letters from the mid-3rd to the mid-5th century are among the most important source texts of church history. They reflect the increasingly prominent awareness of the primacy of the Roman bishops during this period and address aspects of faith, morality, and especially law, which are still constitutive for the Catholic Church today and shape its appearance. Of particular interest are the regulations concerning the celibacy of priests, the ordination of bishops, and the relationship of the Church to the world and the state. The translation is accompanied by a commentary that reflects the current state of research.