Family is the fundamental unit of society, family consist of children, parents, grandparents as it influences the child a lot in the behavioural development.1 In paediatrics child consist of both child and family. Present study conducted to compare the moral and cognitive development of children between nuclear and joint family. Study objectives were to assess the cognitive and moral development of school age children in joint and nuclear family and to compare the cognitive and moral development of school age children between joint and nuclear family. A quantitative approach with Non-experimental descriptive design was used for the study. With Non-probability purposive sampling 50 children from nuclear and 50 from joint family between age group of 10-13 years were selected from schools. Cognitive development assessed by using self-prepared questionnaire and moral development by scale. Reliability of the tool done by split half method. Result showed that there is no difference between children of joint and nuclear family in cognitive development but in moral development there is statistical difference in the moral development