The flock of greylag geese established by Konrad Lorenz in Austria in 1973 has become an influential model animal system and one of the few worldwide with complete life-history data spanning several decades. Based on the unique records of nearly 1000 free-living greylag geese, this is a synthesis of more than twenty years of behavioural research. It provides a comprehensive overview of a complex bird society, placing it in an evolutionary framework and drawing on a range of approaches, including behavioural (personality, aggression, pair bonding and clan formation), physiological, cognitive and genetic. With contributions from leading researchers, the chapters provide valuable insight into historic and recent research on the social behaviour of geese. All aspects of goose and bird sociality are discussed in the context of parallels with mammalian social organisation, making this a fascinating resource for anyone interested in integrative approaches to vertebrate social systems.