This dissertation concentrates on various aspects of the Yiddish dialect and culture in Helsinki. The monograph is divided into two main parts: Historical and Sociolinguistic Perspectives and Linguistic Study. The aims of the first part are to investigate the origin of Helsinki Jewry and their Yiddish and the manifestations of Yiddish in the social and cultural life of the community. The period of time dealt with in this study spans from the first heders of 1860s to the Yiddish articles in the Jewish press of Helsinki in the mid-1950s. The linguistic part of this study investigates the relation of Helsinki Yiddish to Yiddish dialects, chiefly North-Eastern Yiddish sub-dialects, and the way in which the co-territorial languages, i.e. Finland Swedish, Finnish, Russian and Baltic German, influenced the local variant of Yiddish. The general description of the dialect has been compiled on the basis of information gathered from interviews conducted during field-work in Helsinki and Turku.