The title of this book highlights one of Massimo Firpo's major themes: this was not ‘the Reformation in Italy’, just a suboffice of Protestant headquarters further north. It was the Italian Reformation, inspired by Juan de Valdés, a Spanish religious teacher from a converso family. For this English translation, Firpo has chosen two pieces from his awe-inspiring list of publications, and then added other shorter sections, with updated references throughout. The blend works well, illuminating a controversial topic. In Naples between 1535 and the early 1540s, many Italians were captivated by the powerful religious teaching of Valdés. He seemed to believe in salvation by faith alone and in predestination, yet his spiritual tone was different from the teaching of Luther, Calvin and most other sixteenth-century reformers. Valdés stressed individual enlightenment by the Holy Spirit, experience and gradualism, with advice ‘to keep the doctrine in your soul and not on the tip of your tongue’ (p. 51). That last seemingly simple notion would horrify rulers and reformers alike. In 1541 several of Valdés's Italian disciples moved back to central cities. Often they were called spirituali, but Firpo presents them as active people with a mission, determined to spread the Spaniard's message. Publication of small works in Italian was an important strategy, especially their classic Il Beneficio di Cristo (1543). Marcantonio Flaminio, who revised that text, was passionate and energetic but he had essential support from powerful prelates, significantly from Reginald Pole and Giovanni Morone. Yet many of the spirituali had learned a fundamental nicodemism from Valdés (pt i. 5). They were no match for the Inquisition, which took hold of power steadily through the 1540s and 1550s. Firpo's excellent pages probe the complex mix of ‘onward’ and ‘retreat’ in the history and psychology of the spirituali. Even the headstrong Flaminio applied the brakes, warning against ‘most dangerous rocks’ ahead: ‘let us not allow ourselves … to break with the union of the Catholic Church’ (p. 134). In 1547 the Tridentine decree on justification snuffed out long-cherished hopes for reconciliation with northern reformers; Pole was not made pope; he, Morone, Pietro Carnesecchi and many others were pursued in life and in death by the Inquisition. In his last section, Firpo argues that this reformation, slowly crushed in Italy, continued among exiles in other lands, in Switzerland, France, Holland, Poland, Moravia, Transylvania – and, not least, in England. References in this one section are in need of further modernisation, but Firpo makes a powerful case for an authentic diaspora, with radical outcomes. Like many great Italian humanists, this author uses long sentences. Richard Bates had a difficult task, loyally done, but a special translator's dispensation to invent some full-stops would help English readers in future. And there is a promising future for more Firpo-in-English in Ashgate's fine Catholic Christendom series. In a post-confessional era, scholars turn from tired categories of ‘Catholic’ and ‘Protestant’ to re-discover this sfumato reformation. Here it is – from a world expert.