The aim of this study was to examine the contribution of school-related parental monitoring (SR-PM), self-determined motivation, and academic self-efficacy to academic achievement across time. The authors hypothesized that SR-PM would affect academic achievement indirectly via its effects on self-determined motivation and academic self-efficacy beliefs. The participants were 501 adolescents (220 boys; 281 girls) in Grades 6 and 9 as well as their mothers and fathers. We carried out a 2-year, multi-informant study in which the authors assessed SR-PM (maternal and paternal reports), self-determined motivation and academic self-efficacy (self-report), and academic achievement (school records). The authors used structural equation model analysis to test the hypotheses. The analysis shows that SR-PM was positively associated with self-determined motivation and academic self-efficacy and that self-determined motivation and academic self-efficacy affected academic achievement. Furthermore, analyses of indirect effects showed that SR-PM influences academic achievement via its effects on self-determined motivation and academic self-efficacy.