This chapter shows that computer simulations can model the change in attitudes in a population resulting from the interactive, reciprocal and recursive operation of Latané’s (1981) Theory of Social Impact. This theory specifies principles underlying how individuals are affected by their social environment, in particular, how individuals are affected by the strength, immediacy and number of people holding alternative or similar viewpoints. Several group-level phenomena emerge from these individual processes. We describe how the simulations are implemented and some of the parameters that have been included.