On first glance, this seems to be a book about a relatively narrow topic—United States–El Salvador sister city relationships. However, it addresses a host of bigger issues, including theories of human rights, histories of imperialism, and the nature and impact of social movement activism.Sister city relationships began, as Molly Todd explains, as apolitical ways for people in the United States to learn about and get to know communities in other parts of the world. They were often based on similarities in history and geography and driven by the interests of economic and political elites (p. 180). In the 1980s, Central American solidarity activists transformed this model into a unique and, in Todd's telling, highly effective form of activism. This “grassroots sistering” educated US residents about the conflicts that caused suffering in places like El Salvador and Nicaragua and the US government's role in these conflicts; provided direct humanitarian aid to impoverished, war-torn villages; and created opportunities for both US residents and Salvadorans to advocate for policy changes (p. 7). These practices created “an entirely new model of transnational activism” (p. 8).This activism is grounded in the personal relationships that sistering creates between relatively powerful and privileged people in the United States, on the one hand, and vulnerable communities in El Salvador, on the other. These relationships were created, most powerfully, by visits of US residents to their sister cities, where they saw firsthand the hardships that Salvadorans experienced and also learned about their efforts to create new forms of social organization. In addition, many sister city organizations sponsored visits of Salvadoran activists to the United States, where they offered personal accounts of both their suffering and their dreams for a better world.Most United States–El Salvador sister city relationships were between relatively progressive US cities, such as Berkeley, Madison, or Cambridge, and Salvadoran villages in war zones, usually in areas controlled by guerrillas of the Farabundo Martí National Liberation Front (FMLN). The highly politicized nature of life in the FMLN zones of control contributed to a multilayered approach to solidarity work, as sistering activists explain. One layer of such work was purely humanitarian, while another layer was more explicitly political (p. 54). The political dimensions included both opposition to US aid to the Salvadoran regime and support for the work of Salvadorans seeking to build alternative forms of governance and to transform their own society.Todd shows how sistering activists combined concern about traditional human rights issues such as political killings and arrests with the newer concept of solidarity, which emphasizes support for the collective struggle of Central Americans to build a society according to their own vision, without US intervention. The personal relationships created by the sister city model gave solidarity a firm foundation, humanizing the very people whom both US and Salvadoran governments presented as “subversives.”These relationships lasted even after the end of El Salvador's civil war (1981–92), and some of the most interesting aspects of the book are the latter chapters in which Todd details the ways that people in the former FMLN zones of control continued pursuing their political goals in the postwar context. She details efforts to address gang violence, migration, and environmental destruction, as well as the ongoing struggle to hold the government accountable to the reforms laid out by the negotiations that ended the war.Long Journey to Justice is well written, well organized, and easy to read. It makes good use of a wide range of archival material, including many from informal archives—such as boxes of pamphlets and letters in activists' attics. The author's personal notes, such as her own history of activism and her interactions with both Salvadoran and US interlocutors, are interwoven skillfully and enhance the primary focus on archival and other historical documents. While she clearly admires the sister city movement and the Salvadoran and US activists who made it possible, she is careful to analyze tensions, shortcomings, and failures, thus presenting a well-balanced account that does not romanticize its subject. In sum, this is a book that should be of interest to scholars of US and Central American history and politics, to teachers and students in a variety of fields, and to general readers interested in Central American solidarity and related social movements.