This paper is focused on the family as a context for development of formal thinking. Parents’ mediation and cultural tools in family environment were investigated through relationship between formal thinking and the two basic dimensions of family interaction. Psychological autonomy-giving vs. psychological control and emotional exchange were examined in the context of the family's cultural status. For this purpose, the Scale of parents’ mediation means was constructed, inspired by Piaget's concept of formal operations and by Vygotsky’s concept of genetic law. The scale quantifies forms of parent’s behaviors/attitudes towards the child that could serve as mediation means for specific development of formal thinking. The data show: (1) that there is no significant relationship between the two basic dimensions of family interaction and development of formal thinking; and (2) that cultural status of the family and specific parents’ mediation are relevant for child's development of formal operations. .