Lizards exhibit, in a form that is simpler to isolate and study, many of the same traits of higher vertebrates. For this reason, zoologists have long chosen lizards as model systems to address questions that are central to ecological and evolutionary theory. This books brings together many of the most active researchers currently using lizards to study the evolution of social behaviour, plus three experts on behaviour of other taxa for an outside perspective. Each author begins by developing one or more hypotheses, then presents data on a specific lizard system that addresses these issues. The chapters are arranged in three sections that reflect the primary levels at which behavioural ecologists examine adaptive variation in social behaviour: individual variation within populations; variation among different populations of the same species; and variation among several species.