This study examined bidirectional associations between mothers' homework involvement (autonomy support and psychological control in homework situations), Finnish adolescents' academic motivation (intrinsic motivation, extrinsic motivation, amotivation), and school well-being (school satisfaction, school-related stress) across the transitions to lower and upper secondary school. The sample consisted of Finnish adolescents (n = 841; 457 girls; age 12 at T1) and their mothers (n = 652; T1). The results showed that increased levels of maternal psychological control in Grade 7 predicted adolescents' decreased school satisfaction in Grade 9 but only indirectly via increased amotivation. In turn, adolescents' increased levels of school satisfaction decreased maternal psychological control via increased intrinsic motivation within Grade 9 and the first year of upper secondary education. Taken together, more knowledge and understanding should be provided to mothers to help them to support adolescents' motivation and school well-being in more optimal ways. (PsycInfo Database Record (c) 2024 APA, all rights reserved).