Theory, method and conventions -- Historical background of the tonus peregrinus in monophonic practice -- Singled out as a model : the tonus peregrinus in polyphony before 1500 -- The role of the tonus peregrinus in the extended modal systems of Glareanus and Zarlino -- The rise of an idiom : the use of the tonus peregrinus in connection with the French court liturgies of the sixteenth century -- Ambitious obbligo or lack of invention : the tonus peregrinus in Italian-speaking areas during the sixteenth century -- Liberty with rigour : the tonus peregrinus in sixteenth-century Iberian music -- Total thematicism and multi-texted motets : the tonus peregrinus in sixteenth-century Roman Catholic liturgies of northern and central Europe -- "Mit szonderlicher ziemlicher weisz" : the tonus peregrinus in sixteenth-century Lutheranism -- In faburden and upon faburden : the tonus peregrinus in sixteenth-century English liturgies -- One applied and one discreet method : the tonus peregrinus in Roman Catholicism 1600-1750 -- A hand-maiden of many different voices : the tonus peregrinus in Lutheranism 1600-1750 -- The continuing tradition : the tonus peregrinus in music after 1750 -- Conclusions