This paper contributes new evidence and a new perspective to the study of the religious heresy known as Waldensianism in the high-medieval Languedoc, and its relationship to both orthodox authority and the 'Cathar' heresy. Although they were outlawed by Rome in 1184, Waldensians were operating openly in the Cathar lands pertaining to the viscounts of Béziers and the counts of Toulouse and Foix-with clerical complicity. This was until the Albigensian Crusade (1209-29). Its northern French army attacked Cathars and their noble supporters, but began executing Waldensians too. This paper offers a precise chronology and demography for these processes of toleration and persecution. For the first time, it reveals that from 1209, Waldensian refugees relocated beyond the warzone, fleeing to the County of Rodez, the north of the County of Quercy, and the Duchy of Gascony, and were no longer to be found in the Cathar heartlands. In doing this, it sheds light on the wider process of suppressing minority religious groups in the high middle ages, particularly their social and geographical dislocation and assimilation. It also contributes to the related historiographical debate concerning the nature of heresy in medieval Languedoc more generally. 178 words 'Sunt quadraginta anni vel circa': Southern French Waldensians and the Albigensian Crusade Medieval Waldensians constituted an important movement of Apostolic Christianity, devoted to reforming lay religious practice. They were outlawed as heretical throughout Europe in 1184, but the quotation in the title of this paper-'It was around forty years ago'-refers to the recollections of inquisitorial witnesses in Languedoc in the mid-1240s, that Waldensians had operated openly in the region as recently as four decades previously. 1 This remarkable fact relates to the very specific circumstances and nature of their activity in Languedoc. New and re-evaluated evidence offered below indicates that a cautious toleration was the state of affairs right up to the arrival of the Albigensian Crusade, 1209-29. This was launched against lords of the region considered to be harbouring heretics whom historians usually call