Research has shown that family alliance (FA), operationalized as the quality of mother–father-child triadic interactions, is important for child socioemotional development. However, few studies have investigated the predictors of FA, and there are few longitudinal studies available. Accordingly, this study first examined whether mothers’ and fathers’ marital satisfaction and parenting stress during infancy predicted FA five years later, when their children entered kindergarten. Second, the moderating role of both parents’ perspective-taking capacity as a moderator of these longitudinal associations was examined. The study was conducted with 113 intact families (mother–father-child). Marital satisfaction, parenting stress, and perspective taking were reported by both parents and FA was assessed by observation. Contrary to expectations, neither parent’s marital satisfaction or parenting stress was directly related to family alliance. However, significant moderating effects were found for both parents’ perspective taking, such that higher paternal and maternal parenting stress predicted poorer FA only among parents with relatively lower perspective-taking capacities. These findings suggest that some aspects of the quality of family interactions when children enter school can be predicted by mothers’ and fathers’ personal dispositions assessed as early as five years prior.