This book describes to the advanced student how models of animal behaviour are developed, why they are developed and how such models are changed, elaborated and eventually replaced. In each chapter, the author introduces models from a subject area, before going on to consider one or two models in detail. The author outlines how the modellers came to frame their problem in a mathematical form. The later sophistication of each model is described and important factors in the evolution of a behavioural ecological model identified. These include moves towards greater ecological validity, assumption reduction and paradigm shifts. This book should be of interest to advanced students in ecology or animal behaviour with no great mathematical skills.