The body of writing known as Catholic social teaching is often confined to the social encyclicals starting with Pope Leo XIII’s Rerum Novarum. The principles expounded in these encyclicals, however, did not suddenly arise but were distilled from centuries of faith and tradition. In fact, we can trade their origins in the Old Testament. In this paper, I discuss the biblical sources that form the foundations of the social teaching of the Church, starting with the Old Testament.