Books and their reviews have been historically central to knowledge dissemination in the social sciences and humanities. Despite this perceive importance, few studies have assessed the relative importance of these document types in the dissemination of knowledge. This paper aims at better understanding the place of book reviews in the scholarly communication system and to shed light--through the analysis of books on Canada, United Kingdom and United States and their reviewers--on the international circulation of ideas in the social sciences and humanities. Based on 1,675,999 book reviews indexed in the Social Science Citation Index and Arts and Humanities Citation Index over the 1975-2016 period, our results show that book reviews are decreasing in importance in all disciplines—especially those where books have historically been peripheral. We also observe a high rate of homophily between reviewers and reviewed books, with researchers being primarily interested in the books that have been written by someone from their own country. Hence, despite the now widely held assumptions of the globalization of science, social science and humanities remains a highly localized activity.