There is perhaps no more popularized aspect of animal behavior than the things parents do for offspring. Yet our understanding of the evolution of care is only rudimentary, perhaps because parental behavior is one of the most variable behavioral traits we know. Sexual reproduction, particularly in anisogamous species, has a major impact on variable patterns of care. Recent work on conflicts between the sexes over care and the consequences of variable paternity on paternal care has generated fascinating new ideas about the evolutionary forces acting on parenting.