The popular crusades were several movements "animated by crusading enthusiasm" but unsanctioned by the Church. They contrast with the "official crusades" authorised by the Papacy. While the latter consisted of professional armies led by apostolic legates, the popular crusades were generally disorganized and consisted of peasants, artisans and only the occasional knight. The term "popular crusade" is a modern scholarly convention. The distinction between the hierarchical (or official) and the popular "impulse" in crusading was first made by Leopold von Ranke in the nineteenth century. The movements typically regarded as popular crusades are:
- People's Crusade (1096)
- Children's Crusade (1212)
- Shepherds' Crusade (1251)
- Crusade of the Poor (1309)
- Shepherds' Crusade (1320)
- Gary Dickson, "Popular Crusades and Children's Crusade", in André Vauchez (ed.), Encyclopedia of the Middle Ages (James Clarke & Co., 2002 [online 2005]).
- Giles Constable, "The Historiography of the Crusades", in Angeliki E. Laiou and Roy Parviz Mottahedeh (eds.), The Crusades from the Perspective of Byzantium and the Muslim World (Dumbarton Oaks, 2001).