This paper adds to our knowledge and understanding of the time and space dimensions of the shift from an urban penalty to an urban premium effect on the biological standard of living in the second half of the nineteenth century. Although in the literature there is general agreement that urban-rural relations are part of the explanation of declining stature in the period of early economic growth (the so-called Komlos paradox), little is known about its exact timing and spatial dimensions. We use the province of Fryslân, the Netherlands, 1850–1900 as a case study to take a step towards filling this knowledge gap. The area is known for the early modernization of its agriculture, mainly specializing in dairy farming. We would expect a clear development towards an urban premium before 1900, but seek to investigate its timing and placing. This involves running a panel data regression on annual data per municipality, with annual coefficients estimated as interaction effects. The proportion of military conscripts that met the minimum height requirement is the explained variable. Population density and milk supply are the explanatory variables. Our analysis adds to the existing literature on the urban penalty and premium by, first, explicitly focusing on differences over time as well as over space in the relation between urbanization and living standards; second, by using population density data, which is a continuous variable, instead of a simple urban-rural dichotomous variable; and third, by taking into account the importance of dairy farming. The results show that the effect of the availability of milk, the dairy premium, was significantly positive over the period 1850–1900, but remained relatively constant. The effect of population density, however, shows a clear temporality, transitioning from statistically significant negative (urban penalty) to statistically significant positive (urban premium) from 1877 onwards.