Sixteenth-century Lyon bore witness to the ideological and religious upheavals of the Reformation. Printers and publishers were among the first to be influenced by the new ideas of the reformers. One of them, Hugues de La Porte, was on the cusp of the division between the two forms of faith. This very rich publisher and politician had an ambiguous role in the development of the religious identities then under construction. It is very hard for the historian to identify the ‘religious allegiances’ of this reserved and prudent individual who was at the heart of a professional and family network divided between Catholicism and Protestantism.