When the Yiddish atlas project was initiated in the late 1950s by Uriel Weinreich, the prevailing view was that Yiddish was born in the Rhineland in the 9th and 10th centuries when French and Italian Jews adopted and adapted German; it then expanded to the Judeo-Italian settlement in Bavaria and reached monolingual Slavic territory in the 13th century. This third volume (volumes 1–2, 1992, 1995), subtitled The Eastern Yiddish – Western Yiddish continuum, is predicated on the belief that Eastern Yiddish (spoken in central and eastern Europe) is a “colonial” offshoot of Western Yiddish, remnants of which survive in Holland, Alsace, and Switzerland. The 148 linguistic and cultural maps permit the exploration of many questions – including the continuum hypothesis itself; paradoxically, considerable data here seem to disconfirm the hypothesis. The occasional commentary, though not customary in most atlases, is very welcome, though more could have been presented, given the blank space on many pages.