Reflective function is the capacity to reflect on one’s own thoughts and feelings, and those of others. Parental reflective function has been found significant for children’s social and emotional development. However, research has mostly been restricted to mothers and to early stages of development, and there is a paucity of observations on the effects of parental reflective function in later stages. The aim of the present study is to explore the significance of mothers’ and fathers’ reflective function for the adjustment of their children during early adulthood. It is an extension of a previous study that examined the significance of parental reflective function for adolescent adjustment. During home visits, 105 adolescents aged 14–18 years reported on indices of parental behavior (involvement, warmth, and control), and their fathers and mothers were interviewed in order to assess their reflective function. Three to five years later, the participants, now aged 18–22 years, reported on level of symptoms, self-perception, self-descriptions and romantic relations. The findings indicated that parental reflective function, but not parental behaviors that express warmth and control, predicted adjustment during early adulthood. Similar to our previous finding, parental reflective function was associated with both desirable outcomes and possible costs among young adults: higher levels of self-descriptions and romantic relations, on the one hand, and more internalizing problems and less positive self-perception, on the other. It is concluded that parental reflective function affects their children’s adjustment also during early adulthood. However, the benefits of reflective function are inextricably linked to its costs.