Research on family structure has led some to claim that sex-based parenting differences exist. But if such differences exist in singleparent families, the absence of a second parent rather than specific sex-typed parenting might explain them. We examine differences in mothering and fathering behavior in singleparent households, where number of parents is held constant, and we describe individualist and structuralist perspectives for potential sex-based parenting behaviors. We compare 3,202 single mothers and 307 single fathers in the Early