The Protestant Reformation divided western Christianity and was responsible for significant changes in areas that remained Catholic as well. This chapter explores the regulation of sexuality in Catholic Europe – Spain, Portugal, Italy, France, Poland, parts of Ireland, Germany, and Austria – and in Orthodox eastern Europe. The boundaries of Catholic, Protestant, and Orthodox Europe were not stable during the early modern period, as Catholics and Protestants in western and central Europe fought wars of religion for over a century and Christians in eastern Europe fought the Turks. Throughout Catholic Europe – even in France – court cases concerning clandestine marriage were usually brought by one of the parties, not by church or state officials. Many aspects of Catholic teachings about sex and the treatment of sexual issues found parallels in the Orthodox churches of eastern Europe, although there were major differences. The effects of Catholic and Orthodox reform efforts came more slowly and were less dramatic than reformers anticipated.