For more than 2 decades, big-fish-little-pond effect (BFLPE) research has demonstrated that students in high-ability classes and schools have lower academic self-concepts than their equally able counterparts in mixed-ability schools. However, cross-cultural BFLPE research has been limited to mostly developed and individualist countries. Using the Program for International Student Assessment database (Organisation for Economic Co-operation and Development, 2005a, 2005b), the present investigation assessed the BFLPE in 41 culturally and economically diverse countries. In support of the BFLPE, the effect of school-average self-concept was negative for the total sample (effect size = -0.49), negative for each of the 41 countries considered separately, and statistically significant in 38 countries. In this large, culturally diverse sample of countries, the BFLPE was evident in both collectivist and individualist cultures and in economically developing and developed nations. Implications for BFLPE theory and educational practice are discussed. (Contains 4 tables and 4 figures.)