This study examines determinants of father involvement, the parents’ convergence on marital satisfaction, and mothers’ and fathers’ interactive behavior in dual-earner families at the transition to parenthood. Sixty dual-earner Israeli couples and their five-month-old firstborn child were interviewed and videotaped in infant–mother and infant–father interactions. Interactions were coded globally for 21 interactive behaviors and composited into measures of parent sensitivity and infant readiness to interact. Five determinants of each parent’s involvement in house and childcare were assessed as predictors of parent–infant interactions: the sharing of household and childcare responsibilities, the amount of time each parent spends with the infant during the week and on weekends, and the range of childcare activities the parent typically performs. Marital convergence was indexed by the absolute difference score between mothers’ and fathers’ marital satisfaction. Father sensitivity was related to the sharing of household and childcare responsibilities, to the amount of time the father spends with the child on weekends (but not during the week), to the range of childcare activities father performs, and to marital convergence. Mother sensitivity was related only to the sharing of responsibilities between spouses. The range of the father’s childcare activities predicted maternal interactive sensitivity. Infant readiness to interact with the father, but not with the mother, was related to the sharing of childcare responsibilities, to the range of father’s childcare activities, and to marital convergence. Results further specify the differential associations between the marital and the parent–child relationship for mothers and fathers and point to the importance of the father’s instrumental involvement in childcare to the development of fathering. (author abstract)