In this chapter, an introduction is given to palaeodemographic simulation modelling and its application to Roman archaeology. This is illustrated by the case study of the Dutch limes region. It is often assumed that this area could not provide the number of recruits demanded by the Roman army when compared to the available evidence for settlement numbers and sizes. Simulation models based on modern and palaeodemographic data and assumptions on mortality and fertility were set up in NetLogo to test hypotheses on the effects of recruitment on population growth. If it is assumed that soldiers were not allowed to have families, the models show that recruitment of soldiers can have strong negative effects on population size in the longer run. The models were then extended to better understand the effect of marriage strategies and mortality crises such as epidemics on population dynamics. From this, it became clear that the population could have applied various strategies to influence population growth. Also, mortality crises will only seriously curb population growth when they occur frequently. These models, while relatively simple to construct and analyse, are useful to experiment with different socio-cultural, biological, and environmental factors, and can be easily transferred to different settings. We thus see a large potential for this and similar models to be used as heuristic tools that can help to understand the development of population characteristics through time and to assess the importance of the different factors contributing to population growth and decline.