In a clear, precise and readable book, Jonathan Gray forcefully advances his explanation for the success of the Henrician Reformation which he ascribes to the successive oath campaigns. As many scholars of his generation, Gray has taken up the call to examine how the religious and political reforms of the sixteenth century succeeded in winning over popular support. The book essentially substantiates the bold assertion that ‘the oaths were a central way (if not the central way) in which Henry both coerced his subjects into obedience and secured their consent to many of his policies’ (p. 7). The first chapter sets the basis for the argument by laying out the functions and legal requirements of oaths in medieval and early modern England. As form of worship, oaths testified to God's omniscience and omnipotence: knowing the hearts of men he would mete out punishment to those who failed to swear honestly or broke their oaths. Hence, oaths were an ‘ideal means of testing the beliefs of a subject and of binding them to behave in a certain way’ (p. 45) although the question of oaths obtained through compulsion would ultimately weaken their value. Gray painstakingly maps out the plethora of oaths and subscriptions which were required of different sections of the English population between 1533 and 1544. Originally intended to counter the problem raised by the bishops’ oath to the pope and to enforce loyalty, oath-swearing was eventually used against the king's policies by the rebels of the 1536 Pilgrimage of Grace who upheld a qualified version of the Oath of Succession and used solemn swearing to secure popular support. The regime responded by tendering to the rebels an oath which Gray argues had but a limited scope, a sign of the regime's weakness when faced with outright opposition. So, the power of oaths was formidable, exercising both internal and external control over the juror. Made before men, oaths created a form of social pressure and the community promptly castigated perjurors by reporting seditious speech to the authorities. Yet, in the long run, oaths were debased by equivocation as well as by perjury committed by evangelicals and conservatives alike, notably in the context of heresy persecution. Generous in sharing his research, the author provides English translations of Latin texts, an annotated bibliography of manuscripts and the full text of the Henrician oaths in an appendix. This book graciously corrects some mistaken assertions regarding the number, content, enforcement and uses of Henrician oaths but with a purposefully narrow focus in chronology (Henry's reign rather than the entire English Reformation of the title) and in scope, the book engages with only some of the controversies surrounding Henry's reign most notably the amount of power that the government could wield and the evolution of the notion of conscience in early modern England as seen through examples of oath-taking. Gray concludes that the use of oaths increased the power of the Crown in England by providing both a test of loyalty and a mechanism of enforcement, but ultimately it empowered the people by legitimising resistance as the individual's own salvation was at stake.