The big-fish-little-pond effect (BFLPE) was evaluated with 4,461 seventh to ninth graders in Singapore where a national policy of ability streaming is implemented. Consistent with the BFLPE, when prior achievement was controlled, students in the high-ability stream had lower English and mathematics self-concepts (ESCs and MSCs) and those in the lower-ability stream had higher ESCs and MSCs. Consistent with the local-dominance effect, the effect of stream-average achievement on ESCs and MSCs was more negative than--and completely subsumed--the negative effect of school-average achievement. However, stream-average achievement was stronger than, or as strong as, the more local class-average achievement. Taken together, findings highlight the potential interplay of a local dominance effect with variability and/or salience of target comparisons in academic self-concept formations. (Contains 4 tables, 2 figures, and 2 notes.)