The childhood family environment can influence long-term well-being in part by modifying how individuals' respond to and cope with stress across the life span. Theoretical models propose that childhood stress will either exacerbate (stress sensitization) or attenuate (steeling effect) the effects of adult stress on mental health. This study tests whether childhood family stress modifies the association between stressful life events and depressive symptoms in pregnancy and consecutive postpartum periods. A sample of 127 women reported on depressive symptoms after one birth, during a subsequent pregnancy, and postpartum following that birth. Childhood family stress was assessed with the Risky Families Questionnaire. Stressful life events were measured at all three timepoints to capture the number of life events during both pregnancies and between pregnancies. Associations between stressful life events and depressive symptoms varied as a function of childhood family stress. At the between-persons level, more stressful life events were associated with greater depressive symptoms among women who reported infrequent exposure to childhood family stress in this sample, but not among women who reported more frequent exposure to childhood family stress. Results provide novel evidence that moderate exposure to childhood family stress may attenuate the association between stressful life events and depressive symptoms in the perinatal period, consistent with a steeling effect. That is, some degree of childhood family stress may promote resilience to perinatal stress. Findings underscore the utility of examining the interaction of risk factors across the life span in predicting perinatal mental health. (PsycInfo Database Record (c) 2023 APA, all rights reserved).