The purpose of this article is to look at how the Lord's Prayer, with its scriptural base (Matt 6:9–13) and frequent use in late medieval piety, came under careful scrutiny at the Reformation: Luther retained it as central to catechesis and worship; Calvin regarded it as an essential guide to the character of all prayer, but was cautious about its liturgical use; and Thomas Cranmer took a conservative approach, so that it appeared in all the services of the Book of Common Prayer and sometimes twice. Richard Hooker, the late Elizabethan theologian, had to defend Prayer Book usage against Genevans in the English church, who were suspicious of ‘vain repetitions’ – the Geneva Bible's translation of Jesus' warning about prayer (Matt 6:7) – and sought to base his defence by seeing the prayer as an essential part of all worship, both at the daily offices and at the eucharist. Some of his arguments, however, have not stood the test of time, as witness the revisions of the twentieth century, where the prayer is recited only once at each service, and invariably with the doxology – which Calvin favoured, and which Cranmer did not adopt.