In this article we study the evolution of marriage seasonality in relation to economic change, particularly connected to changes in labour supply and work intensity of the kind implied by the ‘industrious revolution’. The focus is on southern Sweden in 1685–1894, which was a period of agricultural transformation and early industrialization, when we would expect to see an increase in work intensity. The analysis is based on about 120,000 marriages from 117 different parishes. The analysis shows that the seasonality of marriage changed dramatically over time, from a classic grain production pattern, with a marriage peak in late spring and a marriage trough at harvest time, to a much more even seasonality, although with the appearance of a very strong peak in December. This change affected rural rather than urban areas, and was present regardless of differences in institutional settings, and for almost all occupational groups below the elite. The changed seasonality pattern is consistent with increasing work intensity over the year, leaving only the weeks around Christmas as a low season. In addition to the increase in work intensity, the privatization of marriage and the availability of time and resources were also important factors in the changing seasonality pattern.