As a political theorist John Wyclif is best known for his writings on lordship (dominium), yet he also addressed the question of just war in numerous sermons and tracts published during the reigns of Edward iii and Richard ii. Wyclif subjected to intense and impassioned scrutiny the three basic criteria for just war as they had been formulated by the medieval canonists and theologians: just cause, proper authority and correct intention. Rory Cox offers the first book-length treatment of Wyclif's views on war; the result is a well organised, detailed and comprehensive study of this cagey, even mercurial, medieval theologian. Cox is not the first to take up this topic, however; for almost a century now, articles and book chapters have been devoted to it. Cox seeks to set himself apart from the pack, therefore, by arguing that Wyclif was not merely critical of the conduct of wars in his own day, but was actually a committed pacifist who was morally opposed to war in principle. In short, according to Cox, Wyclif rejected the very notion of a ‘just’ war, precisely because all war – under any circumstances – runs contrary to the absolutely binding lex Christi. If Cox is correct, this would make Wyclif something of an Anabaptist avant la lettre, eschewing the sword even in self-defence as outside the perfection of Christ (cf. Schleitheim confession vi). The problem, as Cox acknowledges, is that Wyclif never penned a formal treatise exclusively devoted to just war theory. Rather, Wyclif addressed the topic across a wide array of works wherein he voices conflicting, if not necessarily contradictory, views. When taken in their totality, though, we find that Wyclif was by no means sanguine about the prospects of his fellow countrymen waging a genuinely just war; and his deep suspicion of the entire enterprise only increased by the time of the Flanders Crusade in 1383. Whereas previous scholars have generally argued that the combination of Wyclif's wariness of human motives and his commitment to the poor Christ had all but ruled out the possibility of a just war de facto even if not de jure, Cox contends that such an assessment does not go far enough. Anything less than affirming Wyclif as a thoroughgoing pacifist fails to grasp the radical nature of his teaching. This is a bold claim which, in my estimation, cannot ultimately be sustained in the absence of an explicit declaration from Wyclif to that effect. Cox recognises that there is no ‘smoking gun’ which can wrap up this case once and for all. Still, he believes that the sheer weight of Wyclif's frequently dispersed counsels of charity and forbearance is sufficient to tip the scales. Even if the jury is still out on this matter, Cox's thought-provoking book breathes considerable life into a topic that should be of interest to students not only of Wycliffism but of the larger field of late medieval political thought.