ABSTRACT This longitudinal study uncovered prenatal marital antecedents of infants’ attachment configurations with both mother and father at 12-15 months (n = 125). We also examined the contribution of both marital quality and infants’ attachment configurations (secure with both parents, insecure with both parents, secure with mother-insecure with father, and insecure with mother-secure with father) to the quality of triadic (mother-father-toddler) interactions observed two years post-birth. Couples who displayed less negative affectivity and were more emotionally attuned were more likely to have infants securely attached with father and insecurely attached with mother (vs. insecure with both parents) and they engaged in more adaptive family interactions at two years. Also, a secure infant-father attachment relationship forecast more balanced triadic family interactions, regardless of whether the infant-mother attachment was secure or insecure. In contrast, a secure infant-mother attachment relationship was related to less controlling behavior during triadic interactions, regardless of infant-father attachment security.