This study used nationwide data from the Taiwan Education Panel Survey (TEPS) to examine the longitudinal effects of educational expectations and achievement attributions on the academic achievements of adolescents. The sample included 2,000 Taiwanese secondary school students, each of whom completed three waves of questionnaires and cognitive tests: the first in grade 7 (in 2001), the second in grade 9 (in 2003), and the third in grade 11 (in 2005). Through multilevel longitudinal analysis, the results showed: (1) educational expectations accounted for a moderate amount of the variance in academic achievements; (2) students with high educational expectations and effort attribution exhibited higher growth rates in their academic achievements; and (3) studentswith lower educational expectations and those attributing success to others showed significantly fewer academic achievements and significantly lower growth rates in such achievements. The results demonstrated that adolescents' educational expectations and achievement attributions play crucial roles in the long-term course of academic accomplishments. Implications for educational practice and further studies are also discussed.