The use of agent-based modelling and simulation techniques in the social sciences has flourished in the recent decades.The main reason is that the object of study in these disciplines, human society present or past, is difficult to analyze through classical analytical techniques.Population dynamics and structures are inherently complex.Thus, other methodological techniques need to be found to more adequately study this field.In this context, agent-based modelling is encouraging the introduction of computer simulations to examine behavioural patterns in complex systems.Simulation provides a tool to artificially examine societies, where a big number of actors with decision capacity coexist and interact.However, formal modelling in these areas has not traditionally been used compared to other fields of science , specially in their use of formal languages during the modelling process.In this chapter we aim to revise the most relevant aspects on modelling in social sciences and to discuss the use formal languages by social scientists.