This book is about the genetics and behaviour of individuals within colonies of social insects - bees, wasps, ants, and termites. Colonial living is characterized by division of labour and finely coordinated organization, by reproductive function being limited to certain individuals, by cooperative brood care, and by the presence of non-reproductive workers. Within a colony, however, many events are the result of conflicts between individuals seeking to maximize their own interests. Ever since Darwin, this interplay of cooperation and conflict has raised many important questions in evolutionary biology, especially about how cooperative behaviour is maintained in the absence of direct reproduction by workers. How is the heritable component of this behaviour passed on? Crozier and Pamilo's contribution is to analyse the genetic basis of the patterns of reproduction and resource allocation found in social insect colonies. This is done more comprehensively and with greater depth and insight than in any previous study, and is a significant step forward in the fields of population genetics and social evolution.