Starting from the basic idea that identifying predictive family factors for children's well-being is among the levels of the psychology of sustainable human development, our study aimed to investigate the impact of mothers' achievement goal orientations and parental self-efficacy on their children's academic well-being, considering children's own achievement goals as a mediator variable. The entire sample comprised 350 participants: 175 children (42.86% boys) and their respective mothers. Children were enrolled in the 4th grade (n = 85; M age = 10.44, SD = 0.49), in the 8th grade (n = 62; M age = 14.45, SD = 0.53), and in the 12th grade (n = 28; M age = 18.39, SD = 0.62). The results indicated that mothers' motivational orientations had a strong effect on their children's corresponding motivational orientations. Mothers' achievement goal orientations and parental self-efficacy had significant effects on children's well-being, mediated by children's goal orientations. Children's well-being was positively predicted by mothers' mastery and performance-approach goal orientations, with variations between age groups. The importance of the parental motivational orientations in the development of the children's corresponding orientations and well-being suggests that changing academic adaptation might be possible by operating early interventions at the parents' level. Further research is necessary to explore why performance-approach goals had a positive impact on well-being in this cultural context, as previous studies revealed that this type of goal orientation may be detrimental to well-being.Sustainability 2020, 12, 1785 2 of 24 development of children and adolescents (e.g., [6][7][8][9][10][11]). On the basis of the existing parenting models in the literature, three characteristics of parents influencing the development of children were identified: the parents' beliefs (values and goals in socializing their children); the parenting practices they employ; and the parenting style as a more global configuration of different parenting practices reflecting the parents ' beliefs, attitudes, or values [12]. In the scientific literature, parental socialization was captured as a function of two dimensions: responsiveness, viewed as involvement, warmth, or parental sensitivity to the child's states and needs, and demandingness, viewed as claims parents make of the child, strictness, supervision, or disciplinary effort [12][13][14]. Thus, in the research field, different parental beliefs, practices, and styles capturing one of the two aforementioned dimensions or a combination of the two were investigated in order to identify the best parenting practices.However, psychologists in the area of parenting paid special attention to studying parental practices and styles, but they paid scant attention to parents' beliefs [12], which were also related to the child's competences and adjustment in different socialization domains, such as academic achievement.In the present study, in the framework of social-cognitive theory [15], we set o...