Over the past several decades the relatively new field of historical sociolinguistics has developed into a full-fledged subfield of historical linguistics. While placing language change in its social context promises to yield new insights into the mechanisms and motivations for language change, historical sociolinguists are also constrained by the nature and availability of relevant social and linguistic data, and they are challenged by the need to develop appropriate methodological tools. Using specific examples from recent and ongoing research in the development of Early Modern German and Dutch urban vernaculars this talk explores the potential and the limitations of historical sociolinguistic research. At first blush, the limitations seem to far outweigh the potential for real progress. Among other things, researchers are limited to textual data, which means that the literate segment of the population is in most instances the sole source of linguistic data. A second issue is the masking effect that eventual standardization can have on orthographic representation of linguistic variation.
Finally it is notoriously difficult to gain solid evidence of belief systems, conceptions of social class and ethnic identity, gender roles and a host of other social characteristics central to much research in contemporary sociolinguistics. Nonetheless it is possible to isolate patterns of linguistic variation in texts written during a period when any sort of standard language ideology is weak or totally lacking, and there is considerable data relevant to patterns of migration and social interaction that promise to provide insight into the origin of changes in urban vernaculars. In the final analysis I will argue that the primary engine of change in urban dialects is demographic upheaval resulting from high urban mortality and large-scale migration. This demographic instability in turn brings people of heterogeneous linguistic backgrounds into close contact, in many instances at the level of the nuclear family.