The topic of dialectal variation in Basque, a language isolate and the last remaining descendant of the pre-Indo-European languages of Western Europe, has long been a contentious issue in both academic and wider social circles. In The Dialects of Basque, the first major work of its kind in English and a revised version of his bestselling work in the Basque Country, Koldo Zuazo makes two significant contributions to the study of Basque dialects: on the one hand, he introduces a new classification scheme for the different dialects of the Basque language, thereby breaking with the influential categories established by the renowned philologist Louis Lucien Bonaparte in the nineteenth century. On the other, following the pioneering work of experts like Koldo Mitxelena, he contends that the origins of dialectal variation in Basque are not as old as many scholars--including the celebrated Basque specialist Julio Caro Baroja--have argued. Zuazo also observes that, while there is rich dialectal variation in Basque, comprehension among native speakers is not as difficult as has been previously contended. Moreover, he includes in the work more in-depth case studies of the dialects spoken in the Baztan Valley of Navarre and the area around Irun and Errenteria in Gipuzkoa, respectively, as well as a critical examination of theories suggesting the existence of a hybrid Basque dialect in the Americas.