The Ten Commandments, regularly called the Decalogue, derive from the account in the book of Exodus of Moses bringing the tables of the Law down from Mount Sinai. They were reaffirmed and deeply applied by Jesus, not least in his Sermon on the Mount. They thus became part of the Christian inheritance for the next 1,500 years, but, as this Study shows, were rarely if ever prominent as a major source for teaching or morality. The Reformation saw a great change in the Decalogue’s standing. Lutherans, Reformed and Anglicans alike saw it as of central importance in the lives of their congregations, and in different ways gave it that central place in their catechisms, their liturgies and the ornamentation of their buildings. Anglicans in particular can today find the Commandments continued from the Reformation in their 1662 Book of Common Prayer, in both the communion service and the catechism. In the 16th and 17th centuries they were inscribed in central place on the walls of church buildings, in many of which they remain to this day. This Study brings into view the different ways in which the Decalogue impacted the very beginnings of the separate denominational lives of the various Protestant Churches during the Reformation.