This study investigated the relationship between gifted students' academic self-concept (ASC) and academic achievement (AC) in earth science with internationally representative high-school students from the third International Earth Science Olympiad (IESO) held in Taiwan in 2009. The results of regression analysis indicated that IESO students' ASC was significantly correlated with their AC (R[superscript 2] = 0.53, p<0.01) with large effect size, even when compared to other Asian countries such as Korea and Japan. It was found that Taiwan's students had the lowest ASC and exhibited poor interaction with other IESO students. The unique pattern of Taiwanese students exhibited through the 3rd IESO leads to the conclusion that: For the top notch gifted students, their social and psychological character such as their popularity and interaction skills, have much strongly effect on their ASC than cultural factors.