Evidence indicates that maternal prenatal distress predicts problematic health and behavioral outcomes in children as well as infant/child cortisol levels and negative emotionality as reviewed here. Evidence that these physiological and behavioral characteristics themselves moderate environmental effects on development in a "for better and for worse" manner consistent with Belsky's differential susceptibility hypothesis and Boyce and Ellis' notions of biological sensitivity to context raises the prospect that susceptibility to rearing is a function of nurture (i.e., fetal environment), consistent with Boyce and Ellis' proposal that plasticity can be shaped by developmental experience. This hypothesis is supported by new findings from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development showing that low birth weight, a marker for an adverse prenatal environment, predicts infant difficult temperament, which is a susceptibility factor that we previously showed as moderating, in a for better and for worse manner, the effects of parenting and child care quality on socioemotional functioning. Moreover, recent Gene × Environment interaction research raises the prospect that some fetuses may be more susceptible to such "prenatal programming of postnatal plasticity" as a result of their genetic makeup. If this proves true, it will be consistent with the conclusion that early developmental plasticity is a function of both nature and nurture and may be evolutionarily adaptive, a further possibility considered in the discussion.