This paper is more concerned with posing questions than attempting to provide answers. I am principally interested in trying to establish whether there was a connection between the English Arminians’ emphasis on ritual and the beautification of churches in the 1620S and 1630S and the perception at the time that Roman Catholicism was gaining ground, especially in London and at the court. It has long been known that Charles I’s court was considered by contemporaries to have been rife with Catholic activity. Likewise, the embassy chapels in London provided a focus for Protestant discontent as a result of their attracting considerable congregations of English Catholics. The 1620s also saw the Arminian faction within the Church of England grow in influence, acquiring the patronage of the Duke of Buckingham and of King Charles himself. As has been demonstrated by Nicholas Tyacke, for example, this faction was very much orientated towards the court, and gained power by working within this milieu under the leadership of Laud and Neile. However, I am not concerned here with the politics of the Arminian rise to control of the Church of England hierarchy, but rather with their interest in ceremonial worship, their endeavour to place liturgy rather than the sermon at the centre of services. Was a leading Arminian such as John Cosin, for instance, reacting to what amounted to a Roman initiative? Furthermore, one needs to ask what part aesthetics played in attracting and retaining the allegiance of Catholics to what was, after all, an illegal form of worship. Even if the no longer faced the likelihood of physical martyrdom, financial penalties were severe, and the threat of imprisonment remained for priests and laity alike. Yet some twenty per cent of the titular nobility and many ordinary folk remained loyal to Rome. May not the very nature of Catholic worship provide a clue to explain this phenomenon? Clearly this is an extremely wide subject, which the time and space available does not permit me to explore in depth on this occasion. Therefore, I propose to focus on two specific areas: what attracted crowds of Londoners to the Catholic worship offered by the embassy chapels; and on one aspect of the Arminian response, namely, the field of devotional literature. I shall examine John Cosin’s A Collection of Private Devotions… Called the Hours of Prayer (1627) in the context of its being a reply to popular Catholic devotional books of the period, such as the Officium Beatae Mariae Virginis, commonly known as the Primer. Thus I shall address issues connected with both public and private devotions.