This thesis examined the influence of parents' gendered attitudes and behaviours on three different aspects of development in middle childhood and early adolescence through three papers. The first paper explored the longitudinal influence of parents' gender-role attitudes and division of household responsibilities on children's gender development. Results showed that parents' gender-role attitudes and division of household responsibilities were predictive of children's gendered personality traits, gender-role attitudes and feminine preferences for activities, but not their masculine preferences for activities. The second paper investigated the influence of parents' gender-role attitudes and division of household responsibilities on children's ability self-concepts. Parents' gendered attitudes and behaviours were not predictive of children's ability self-concepts. However, children's own gendered attitudes and behaviours were associated with these self-concepts. Children's higher feminine preferences predicted lower maths and sports self-concepts and higher English self-concepts. In addition, higher masculine preferences and personality traits predicted higher sports self-concepts. Finally, the third paper explored the influences of parents' gender-role attitudes and division of household responsibilities on sibling relationship quality, and marriage and parenting as mediators of this association, which is unique to the literature. Families with more egalitarian division of household responsibilities had more positive and less negative sibling relationships than traditional families. Using structural equation modelling, parenting, but not marriage was found to act as a mediator. Papers 1 and 2 used a longitudinal sample of 106 families with two siblings and their parents from the South East of England. Paper 3 used just the first wave of data from this study which included 124 families. This research highlights the importance of taking a family systems approach to examining child development, and emphasises the need to explore the father-child and sibling relationships in addition to the prevalent focus on mother-child relationships. In addition, multiple dimensions of gender were explored for parents and children rather than just examining sex differences. This added extra depth to the analysis and aided in understanding the complexity of these associations. The diverse nature of influences of parents' gendered attitudes and behaviours on these three areas allows comparisons to be made that contribute to the literature on parental influences and our understanding of child development in middle childhood and early adolescence.