Part I Agent-Based Models: 1 Introduction.- 2 Simulation and Artificial Life.- 3 Making the Artificial Real.- 4 Modelling in Population Biology.- Part II Modelling Social Systems: 5 Modelling for the Social Sciences.- 6 Analysis: Frameworks and Theories.- 7 Schelling: A Success for Simplicity.- 8 Conclusions Part III Case Study: Simulation in Demography.- 9 Modelling in Demography: From Statistics to Simulations.- 10 Model-Based Demography in Practice: I.- 11 Model-Based Demography in Practice: II.- 12 Conclusions.