Introduction: The forty passiones translated in this volume represent a genre of Christian-Latin literature that has seldom attracted attention and is poorly understood; yet in sum they constitute a remarkable body of literature composed during the period between 425 and 675, and provide valuable evidence of the sentiments and beliefs of ordinary Christians of that time — their aversion to pagan practices, their admiration for virginity, their firm commitment to orthodoxy — as well as evidence for the machinery of Roman legal procedure. Since the passiones appear to have been composed by the clerics who were custodians of the martyrial churches and shrines in Rome, in response to the ever-increasing volume of pilgrim traffic to these shrines, and since these clerics appear not to have received the benefit of the highest grade of Roman education, they provide first-hand evidence for the sub-élite Latin of the time. The passiones are works of pure fiction: they abound in absurd errors of chronology, and of the Roman magistrates who figure in them, very few can be identified (this is one of the reasons why the passiones have largely been ignored by historians of late antiquity). Of the forty passiones, some twenty-one treat martyrs who are attested in sources earlier than c. 384, and who may be considered ‘authentic’ martyrs (which is not to say that the descriptions of their arrest, trial, torture and execution — which are often described in ludicrous terms — are similarly ‘authentic’). The remaining passiones treat persons concerning whom there is no reliable evidence that they were martyrs: some are the names of pious persons who donated property to the church; others are the result of pure invention. In any case, there is very little evidence that large numbers of Christians were martyred at Rome in the period before the ‘Peace of the Church’ (c. 312): certainly not the large numbers implied by the fictional passiones. No records of trials of Christians from the period before c. 312, so for their accounts of the trials the authors of the fictitious passiones were obliged to model their accounts on genuine accounts of trial proceedings involving Christians in proconsular Africa (the so-called acta proconsularia); but many features of the trials described in the passiones are imaginary: for example, the lengthy debates between the presiding magistrate or judge and the martyr on questions of Christian belief (the virtues of virginity, the evils of paganism), some of which devolve into lengthy sermons by the martyrs. In any case, the martyrs in the passiones never succeed in converting the judge, and are accordingly sentenced to torture (often described in excruciating, and sometimes absurd, detail) and execution. In most passiones, the bodies of the martyrs are recovered by pious Christians and buried in identifiable shrines (usually in suburban cemeteries).