Cooperative breeding occurs where more than two individuals combine to rear a single brood of young. It is extraordinarily prevalent in the Australian avifauna, for both phylogenetic and ecological reasons, and we are conducting a number of studies to understand this prevalence. Current work focuses on superb fairy-wrens and woodswallows, though we have worked with kookaburras, bee-eaters, kingfishers, thornbills, choughs and parrots.