The purpose of this study was to examine the relationship between successful intelligence and middle school students' academic performance. Data was collected through the successful intelligence test developed and revised from the Sternberg's Comprehensive Ability Test and the 2007 province-wide standardized tests. 140 male middle school students participated in this research. Three statistical methods of correlation analysis, multiple regression analysis, and ANOVA were adopted for the data analysis. Results are as follows. First, positive correlation coefficients were found between analytical, creative, and practical intelligence, and student achievements, all of which were statistically significant. Analytical intelligence, especially, was the most highly correlated variable with all subject areas. In addition, it was also the only predictor in successful intelligence in the achievements of all the subjects. It also revealed that creative intelligence was another predictor to math performance and that practical intelligence was a predictor to science performance. Second, students in the consummate balancer group showed higher achievements than those in the other groups. In addition, students in the groups of complex profiles such as creative practitioner, analytical creator, and consummate balancer did better than students in the single profile of low intelligence in the tests. Results of this study are important in that successful intelligence could be a good foundation for implementing differentiated instruction as a way of matching instruction to the aptitudes of students.