Nesting and parental behaviors of modern crocodilians, and ratite and megapode birds are surveyed and reviewed to provide a data base for work on dinosaurian nesting and parental behavior. The modern analogs provide information on prenesting territoriality, mating systems and pair formation, selection of a nest site, construction of the nest, method of incubation, parental attendance of nests, properties of eggs and nests, parental assistance to young at hatching, hatchling vocalization and gregariousness, posthatching parental care, and dispersal of the young. Nest construction for the group includes simple depressions, excavated holes in which eggs are buried, or mound-nests of leaf litter. Incubation temperatures may be maintained passively by nest design and siting, or the temperature may be raised by direct body contact, solar radiation, geothermal heat, fermentation of litter, or a complex combination of several heat sources. Parental behavior is independent of physiology. Ectothermic crocodilians commonly guard nests, assist the young at hatching, and may protect the young after hatching. Some endothermic megapode birds abandon eggs immediately after oviposition. Evidence for dinosaur behavior is equivocal on many points, but data from taphonomy, ichnology, eggs, and nests suggest several behaviors, including: gregariousness by both adults and juveniles; vocal and visual signaling to defend territories, establish hierarchies, and attract mates; egg burial in moist sand or leaf litter; male participation in guarding nests and providing care to young; colonial nesting; parental attendance at nests; pod formation by hatchlings; possibly vocal communication between hatchlings and adults; and possibly parental protection of hatchlings.