Parental (parent-to-infant) attachment and parenting alliance are defined as two important components of psychoaffective adjustment to the parental role. This study aimed to build a predictive model of parental attachment and parenting alliance for mothers and fathers using partial least squares-structural equation modeling. Specifically, we were interested in assessing how adult romantic attachment, marital quality, and psychological distress influenced parental attachment (parent-to-infant) and parenting alliance. Forty heterosexual couples completed questionnaires during the third trimester of pregnancy and 2 months after childbirth. Results showed that adult romantic attachment, marital quality, and psychological distress were important antenatal determinants of parental attachment and parenting alliance, although they behaved differently for mothers and fathers. Hence, different predictive models were therefore proposed for mothers and fathers. Mothers' attachment to the child was influenced by internal factors as adult attachment dimensions; for fathers, it also depended on mothers' antenatal attachment to the child and on marital quality. Concerning parenting alliance, both mothers and fathers depended on own and partner's variables. Antenatal variables are important for what occurs during the transition to parenthood in terms of parenting adjustment and act differently for mothers and fathers. It thus is important to assess the psychological functioning of both mothers and fathers.