As a political history that extends from pre-Islamic times to the 2011 resignation of Yemeni President Ali Abdallah Salih, Stephen Day's Regionalism and Rebellion in Yemen is impressive in its comprehensive scope and its rigorous detail. The book contributes to the emerging literature examining the underlying historical drivers of the various 2011 Arab Springs. What marks Yemen as unique, according to Day, is that the regime's fall was not a surprise in 2011. Salih had been experiencing open rebellion for at least four years. Rather, the Arab Spring brought multiple groups together in their opposition to Salih and, most importantly, in so doing, provided Yemen with a second chance at national unity. The book thus is a painstaking analysis of the country's fragile national identity, focusing on the role of regional divisions and dynamics related to the problematic unification of the former Yemen Arab Republic (North Yemen) and the former People's Democratic Republic of Yemen (South Yemen) in 1990 and, following that, in the upheavals of the 2000s.

The book's main thesis is that the former president and his closest associates from the northwest highland region maintained power through a combination of patron-clientelism, establishing clientelistic relations with various groups in other regions of the country, and divide-and-rule between regional clients. These relationships not only were self-serving and exploitative but also ultimately led to the strengthening of regional identities at the expense of a shared sense of national belonging. The causes of the 1994 civil war and the “return of Yemeni regionalism,” according to Day, lie squarely with the political leadership of the former North Yemen, namely Salih. With unification and the addition of three or more regional groups to the political mix, Salih found it increasingly difficult to maintain political stability via these strategies. Sealing his fate was the rise of a powerful opposition within his own highland region.

Nine chapters deal with four additional factors that Day highlights as necessary for understanding Yemen's politics: the history and traditional makeup of Yemeni cultures and societies; the power structure of Salih's regime and, in particular, the dominance of his northwest highland group and the system of patronage he employed; the flawed process of unification in the 1990s; and the political and economic policies of the 2000s. The author traces the consequent rise and politics of three regional groups in particular: Al Qaeda on the Arab Peninsula, the al-Huthi movement, and al-Hirak. He concludes with a detailed account of the events of 2011 and his argument that Yemen's best hope for the future is to build on the new solidarities created during the 2011 uprising in order to restart Yemeni national unity on more favorable terms.

The book is based on research spanning 17 years, and Day's in-depth knowledge and personal familiarity with the country is evident. In addition to secondary research and an incalculable number of interviews, his argument is supported with a first-of-its-kind survey of provincial administrators (1985–97), demonstrating the dominance of appointed government officials from the northwest highland region.

Day's premise that an understanding of Yemen's regionalism is key to understanding the country's politics springs partially in response to studies, largely from the 1990s, that, he argues, were caught up in the unionist spirit following formal unification and consequently denied the existence of multiple regional divisions. For Day, a Yemeni national identity never existed. In his words, “the national union of the Yemeni people is only an imagined social construct…. In other words, Yemen's national union is not a given, natural state to which the country's population returned in 1990” (p. 14). United Yemen as an imagined community will only exist, he states, with the fair and equitable distribution of resources. Resource competition plays a pivotal role in the formation and maintenance of group identities. However, while the author's account of regional rebellion competently demonstrates the mobilization of group identities as a result of political and economic policies, the formation or social construction of these identities is covered in far less depth, with regional identities appearing to be primordial, almost innate. Indeed, Day calls for a form of “primordial federalism” (p. 309) as the solution for Yemen's future.

The author's conceptualization of regionalism and how it relates to other forms of identity also remains relatively unclear. For Day, the country's various contestants for power, whether tribal or sectarian, not only are found in specific regions but also emerge from and are expressions of regionalism. Yemen's geography thus plays an almost deterministic role in isolating regions from each other and creating the conditions under which different regional dialects, traditions, and identities develop. While few would deny Yemen's geographic diversity or the fact that there are clear expressions of regionalism, the extent to which groups identify and mobilize as a result of tribalism, for example, or whether they do so as a result of regionalism that expresses itself in tribal markers, remains a nagging question for the reader. Day's discussion is relatively unhelpful when he states, for example, that “Yemen's seven regions are based on loose social structures, inside which regional group bonds are weak compared to other social bonds like tribal and clan affiliations. Tribes and clans create the most powerful group bonds inside Yemen” (pp. 44–45).

With regionalism the focus of Day's analysis, Yemen's vibrant civil society makes little to no appearance in the book. While civil society may not be considered of central concern to the author's argument, three actors that are integral to his account and would have benefited from greater analysis are the Islamist Islah Party, the Joint Meetings Party (JMP)—a coalition in which Islah is a member—and the opposition within the northwest highland region. Given Islah's substantial popular support, the role it played in the 2011 uprising, and the role it is playing in post-Salih Yemen (as is the case with Islamists in other post–Arab Spring countries), a deeper discussion of Islah would have been justified. Similarly, the significance of the JMP as the first coalition of Islamists and leftists—expressing precisely the type of solidarity Day deems as important to Yemen's future—and the key role it played in the cancellation of the 2009 parliamentary elections warranted greater attention. Lastly, the book also would have benefited from a far greater discussion of the rise of the opposition within Salih's highland region. While Day considers this opposition the strongest indication of Salih's inevitable downfall, he devotes relatively little attention to the conditions under which it developed.

These weaknesses aside, Regionalism and Rebellion in Yemen must be commended. Day ably presents a complex political history with multiple players of diverse regional, tribal, ideological, and sectarian backgrounds in a manner that is accessible to nonspecialists, while simultaneously providing detail and analysis from which Yemen specialists can benefit. His deep affection for Yemen and its peoples is clear and expresses itself in references to the customs, dialects, and even the architecture of its cities, making the book highly enjoyable to read. Substantively, Day provides an excellent analysis of the Salih regime's strategies to maintain control and of the mobilization of the regionally based groups that ultimately helped to bring down the president. His account offers much to students of Yemen and of Arab Springs elsewhere.