The purpose of this study was to find the relationships between the "triarchic abilities", based on the "Sternbergs theory", and the academic achievement. Three hundred and sixty students in grades 7 and 10, from the mainstream and gifted schools, participated in the study. The results revealed that the "Creative ability" was the most important factor which predicted the academic achievement. In particular, for the mainstream students, achievement in Math (in grades 7 and 10), Art (in grade 7), and Physics (in grade10) were associated with the creative ability, while for the gifted students, this association was found only for grade 7 in Professional and Technical course. Furthermore, it was found that the "analytic ability" can predict the achievement in sciences, religious and composition courses only for the mainstream students in grade 7.However, the "triarchic abilities" did not indicate significant relationships with academic achievement for the gifted students. In conclusion, analyses showed that the mental abilities of the gifted students in grade 7 were higher than their classmates in the mainstream group, while, for the students in grade 10, similar result, was found only on the "practical ability" between the gifted and mainstream groups.