We revisited a theory called the big-fish-little-pond effect (BFLPE) that an individual student’s academic self-concept was negatively affected by their schools’ academic achievement levels. By analyzing PISA 2006 and PISA 2012 data, this study attempts to provide empirical support for conceptual differences between self-concept and self-efficacy under the theoretical framework of the BFLPE. This study examined the BFLPE on the academic self-concept as well as self-efficacy. We also examined if the BFLPE was consistent on different achievement domains (science vs. mathematics) across countries using multilevel analyses. The results show that the BFLPE appeared universal for students’ self-concept in both science and mathematics across OECD countries, but the magnitudes of the BFLPE appeared slightly larger in math than in science. However, the BFLPE was not consistently found in the academic self-efficacy. We discussed the different results between the academic self-concept and self-efficacy based on the previous literature.