Investigations into dialect emergence are most often based on data from manuscripts and on comparative and internal reconstructions. Seldom does the opportunity arise to monitor the selection of competing norms during the emergence stage because the data to postulate the linguistic marketplace (and hence to know what forms were likely to have been in competition) are unavailable. The case of dialect emergence in Thyborøn, Denmark, over the past century offers just this rare opportunity. A historical demographic profile from the town's census data, dating back to its inception in the 1890s, enables a comparative analysis of the input dialects and variable linguistic forms that were in competition. It is possible to trace the linguistic and social variables at play during the emergence stage of this new dialect, following the tradition of research by Omdal (1977), Dorian (1981), Trudgill (1986), and Kerswill (1994b), among others. The findings contribute to an explanatory model of dialect emergence and transformation.