The decline of Mithraism in the fourth century AD is used as a case-study for understanding the end of other classes of 'paganism' in the Roman western provinces. The author reviews epigraphic and numismatic evidence to date the final uses of Mithraea. He then discusses examples of wilful damage to Mithraic monuments. Drawing all this archaeological evidence into a historical framework, Sauer argues that rather than losing its social function as the Roman army became splintered, Mithraism was a healthy religion with active shrines until the very late fourth century. Rather than fading away, its desecrated monuments indicate that the religion was the victim of a sustained Christian attack which was also directed at other established faiths in the western provinces.