In Switzerland, school is strongly regulated by law on a provincial level (cantons). Therefore, rules on parental involvement vary between the cantons. Law regulates topics such as mutual child-related information of teachers and parents, power of parents and teachers in school career decision-making, school control of healthy child development, and parental organisation on a school level. Theory and research focus on topics such as the relationship between school and families on structural and functional levels, the cooperation between parents and teachers, effects of families on student motivation and achievement, effects of families on school careers (track placement, social inequality, etc.), the training and counselling of parents and the training of teachers to prepare for cooperating with parents. Research was carried out at school, classroom and individual levels. As an example, the results of a longitudinal study are presented on how parents’ attitudes and activities in contrast to student intelligence influence student achievement and track assignment at the end of elementary school.