A number of authors ( 1 I) have proposed · that the effects of posrmual handling ~re mediated by changes in mother-pup interactions and that the handling manipulation itself might map onto naturally occurring individual differences in maternal care. Speciiically, Levine proposed that handling of the pups altered the behavior of the mother and that these differences in mother-pup interactions then mediate the effect of handling on the development of endocrine and behavioral responses to stress. The question, then, is how this maternal mediation might occur and whether such factors might contribute to naturally occurring individual differences in HPA responses to stress.