This short monograph lays out the theory behind, and techniques for, using dynamic modelling, taking the reader through a series of increasingly complex models. At each step, examples are used to explain the process, and also to clarify specific applications of difference equation models in the social sciences. 'It is a good example of classical mathematical model building and I may well use it as a text for the course on that subject in our MSc on Quantitative Methods in the Behavioural Sciences...in general it is to be recommended.' -- Bethlem and Maudsley Gazette, Vol 31 No 2, 1983