Individual demographic behaviour cannot be understood in isolation from the social network one is linked to. However, formal models of demographic behaviour lag behind the empirical evidence. In this chapter we demonstrate how agent-based models can be applied to investigate the role of social interactions to explain macro-level demographic patterns like the age-at-marriage curve, age-specific fertility rates and the role of family policies for fertility. Based on these three examples we discuss the various steps that need to be followed when building up an agent-based model. These include the choice of the characteristics and rules of the agents together with the definition of how agents may interact and how macroeconomic behaviour may feed back on the micro-level decision processes.