The rapid progression of Chilean politics over the last few years has been astonishing to behold. It started with an outbreak of mass protest in October 2019. That outbreak, or estallido, led to a national referendum in October 2020 to approve the writing of a new constitution and the election in May 2021 of the constituents charged with writing that new constitution. The year ended with a hard-fought presidential election that made a former leader of the student movement the country's youngest chief executive. Given the boldness with which Chileans are now moving to change the basic rules of their republic, Pablo Ruiz-Tagle's history of Chilean constitutionalism comes at a welcome moment.Ruiz-Tagle is well positioned to offer such a study. As a practicing attorney, professor of constitutional law, and dean of the University of Chile's School of Law, he has been involved in the country's constitutional debates for three decades. Five Republics and One Tradition is a translation of his book Cinco repúblicas y una tradición: Constitucionalismo chileno comparado, published in 2016 by LOM Ediciones in Santiago. The translator has done an adequate job of sorting out the author's extensive use of legal terminology, although the reader will struggle at times with some awkward phrasing in the text. Sadly, the English translation does not bring readers up to speed on developments since the October 2019 estallido. It does, however, provide insightful commentary on Chile's four main constitutions, those of 1828, 1833, 1925, and 1980.The book presents a complex legal, political, and historical argument about Chile's tradition of “republican constitutionalism” (p. 14). One part of that argument has to do with the existence of the five republics. Borrowing from French historians, Ruiz-Tagle sets up the book as a series of chapters dealing with each of Chile's five historical republics, which he describes as independent (1810–30), authoritarian (1830–70), liberal (1870–1924), democratic (1932–73), and neoliberal (1990–present). Within that historical framework one finds two notable gaps in the timeline—one from 1924 to 1932, a period of political turmoil, military intervention, and progressive reform; and one from 1973 to 1990, the period of General Augusto Pinochet's dictatorship.This part of the argument is mostly convincing and enlightening. Each chapter is rooted in the author's deep knowledge of constitutional scholarship in Chile and the United States (the author, a Yale Law School graduate, makes several references to the Founding Fathers as well as US constitutional law scholar Bruce Ackerman). Historically speaking, the chapters are thin on content. On the one hand, the author displays a strong grasp of the classic historiography on Chilean politics; on the other hand, the book does not reflect more recent thinking by historians in Chile and elsewhere about the relationships between constitutions, elections, and popular politics.In terms of the evolution of Chile's constitutional legal doctrines, however, the chapters are rich. The author's explication of the changing conception of property law is perceptive, especially his emphasis on the importance of the concept of the “social function of property” embedded in the 1925 constitution, which opened the door to the land reforms of the 1960s and industrial expropriations of the 1970s (p. 120). Another important concept in Ruiz-Tagle's view is that of “constituent power,” by which he means the power of the majority of citizens to have its will carried out under the rule of law (p. 264). The author deftly explains that, under the Pinochet dictatorship, the military junta claimed constituent power for itself and used it to legitimate the enactment of the 1980 constitution. The chapter on the “Fifth Republic,” or “Neoliberal Republic,” is by far the most detailed, offering a strong critique of its “presidentialism” as well as an extensive analysis of its “doctrines regarding the right to property” (pp. 160–61, 217–38).Unfortunately, the other main part of Ruiz-Tagle's argument is unconvincing—namely, his insistence on the singularity of the republican constitutional tradition in Chile. Whereas the book's title posits the existence of “one tradition” in Chilean constitutionalism, various passages within the book acknowledge the coexistence of a powerful “anti-republican” tradition, one that can be seen as parallel to the liberal-republican tradition that Ruiz-Tagle so clearly embraces (pp. 16–19). The author thus casts the dictatorships of the twentieth century as violent disruptions of that “one tradition,” but in so doing he analytically disconnects them from the antirepublican forces that were present in all five republics, most notably the “Authoritarian Republic.” As the national elections held since the end of the Pinochet dictatorship demonstrate (including the most recent presidential election), a solid 40 percent of the Chilean electorate remains sympathetic to a law-and-order message that hearkens back to the days of Diego Portales. In other words, the “one tradition” posited in the book's title may not reflect the more complicated reality of Chilean political history.