With Mexican exodus, Julia G. Young offers an outstanding contribution to the fields of Mexican migration, the Cristero war and Mexican American Catholicism. In this concise, clearly written text, Young chronicles the activities of Mexican emigrants who supported from afar the Cristero war, a 1926–9 rebellion by militant Catholics against an anticlerical Mexican government. Specifically, Young details the tangible effects of their activities on the war and on early Mexican American community formation in the United States. Her methodology – framed as ‘transnational’ – is impressively broad-ranging, from archival research in the United States and Mexico to oral interviews with surviving members of emigrant families. And, among other historiographical arguments, Young makes a few key assertions. First, alongside scholars such as Benjamin Smith, Young finds that negotiation, not conflict, broadly characterised the laity's relationship with the ecclesiastical hierarchy. This challenges a general assumption that a radicalised laity largely carried on the war unassisted, while conciliatory prelates awaited their chance to strike a truce with the state. The strength of this study, in fact, lies in Young's close examination of the exiled Mexican clergy and their relationship to ‘Cristero partisans’ (p. 17). She sympathetically narrates the rise and fall of Cristero leaders in the United States such as José Gándara, as at first a militant clergy worked alongside them in open rebellion, and then a more conciliatory hierarchy shunted them aside in favour of a truce with the Mexican government (pp. 92–100). Second, along with scholars such as Matthew Butler, Young asserts that religious motivation has explanatory power. Mexican migration to the United States, especially in the late 1920s, cannot be explained in purely economic terms. Moreover, ‘[f]or tens of thousands of Mexican emigrants, religion – and religious activism – would come to be an essential part of community formation during the 1920s, and in subsequent decades’ (pp. 59–60). In her final two chapters, Young brilliantly points to the rise of a ‘Mexican Catholic nationalism’ (p. 129) among Mexicans in the United States as a reaction to the anticlerical Mexican government. But her emphasis on ‘diaspora’ and Cristero partisans’ ‘familial, political, and economic ties’ to Mexico leads her somewhat to neglect a broader US context. There is little discussion of the repatriation of a third of the entire Mexican and Mexican American population in the United States from 1929 through the early 1930s, for example. And while she details the efforts of the US hierarchy to welcome Mexican emigrants with open arms, there is only a brief mention of the ‘persistent racial prejudice and discrimination by non-Mexican’ parishioners (p. 47). There is no mention of the brutal violence directed against thousands of people of Mexican descent along the Texas border at this time. It seems at least possible that a ‘Mexican Catholic nationalism’ was as much a reaction to a hostile US religious and political environment, as it was to problems in the homeland. Notwithstanding this minor critique, Mexican exodus is essential reading for students of the Cristero war and Mexican migration to the United States.