Swarm intelligence is an important and popular branch of computational intelligence. This technique is based on the analysis of the collective behaviour of swarms in nature and of social phenomena, and it is aimed to solve highly non-linear problems. The optimization performances of these techniques are highly affected by the specific choice of the working parameters. In this chapter, the modelling of interaction in swarm intelligence is done by means of different models, and the space of the working parameter is finally divided accordingly to the specific dynamic behaviour of the swarm for each point of this space. In this analysis, the attention has been focused in two optimization algorithms: the well-known particle swarm optimization an...