The study aims to investigate the development of family interactions from pregnancy to preschool age in a longitudinal perspective, using multilevel analysis. Also, it explored the impact of couple relationship and father involvement in childcare on the developmental trend of the quality of mother\u2013father\u2013child interactions. One hundred and three primiparous families were assessed at 7th month of pregnancy, 4th, 9th, and 18th months of child\u2019s life and during preschool age (36\u201348th), using the observational procedure named, Lausanne Trilogue Play. Parents\u2019 perception of marital satisfaction was assessed with the Dyadic Adjustment Scale at each point of measure; moreover, in the postnatal assessment, parents completed the Father Involvement Questionnaire. Results showed that family interactions increase over time. Secondly, a decrease of marital adjustment is associated with an improvement of the quality of family interactions. Moreover, father involvement predicts the quality of family interactions from the earliest stages of child\u2019s life. In a longitudinal perspective, family interactions and marital quality show opposite developmental trends and father\u2019s involvement represents a particularly important feature of the family