In the peripartum, putative mechanisms in the transmission of prenatal contextual risk and maternal psychological distress include biological and social processes. In this study, path analyses were used to test unique, cascading pathways of prenatal contextual risk and pre- and postnatal maternal psychological distress through social mediators (parenting) and biological mediators (infant stress physiology) on infant temperament and toddler adjustment. The sample is comprised of racially and ethnically diverse first-time mothers (N = 200) living in low-income contexts (< 200% poverty) who were followed from pregnancy to 18-36 months postpartum. In pregnancy, mothers reported contextual risk and psychological distress (anxiety, depression). In the postpartum, mothers reported their psychological distress. At 2-4 months postpartum, observed mother-infant interactions were coded for sensitive responsiveness. Infant cortisol baseline and reactivity to a lab stressor were collected when infants were 4-6 months old. Mothers reported on infant's temperament (negative affect, effortful control) at 10-12 months and on child adjustment (internalizing, externalizing symptoms) at 18-36 months. Prenatal contextual risk predicted infant cortisol reactivity. Prenatal psychological distress predicted postnatal distress but, when accounting for postnatal distress, did not predict putative mediators or indicators of child adjustment. In contrast, maternal postnatal depression predicted subsequent maternal sensitive responsiveness, which in turn predicted later infant baseline cortisol and cortisol reactivity. Baseline cortisol predicted infant negative affectivity, which predicted toddler internalizing and externalizing symptoms. There was no evidence of mediated effects of prenatal variables on child adjustment outcomes, whereas contextual risk, postnatal psychological distress, and parenting were more salient predictors of child adjustment. (PsycInfo Database Record (c) 2024 APA, all rights reserved).