No general consensus has been reached, as yet, on how to interpret sixteenth century Italian demographic dynamics. Such divergences reflect different convictions about the relationship between population and resources. On the basis of 164 series of baptisms celebrated in northern Italian parishes and adopting a comparative perspective, this paper progressively evaluates the demographic weight of environmental factors (location in lowland, mountain or coastal areas; urban or rural environment; for rural areas, different settlement patterns and crop regimes), and provides new insight into the relationship between population and resources (Malthusian, “Boserupian”, or something else?). The paper reveals a complex situation, where environmental and socioeconomic factors have an impact not only on demographic trends but also on the very model of population change, and where advances in agrarian technology do not always play a demographically positive role.