Background: On the one hand, achievement indicators like grades or standardized test results are strongly associated with students' domain-specific self-concepts. On the other hand, self-evaluation processes seem to be triggered by a self-enhancing means of information processing. As a consequence, above average students have more positive self-concepts than average students whereas below average students have lower self-concepts than average students. Aims: Imagine that two students, one above average, the other below average, have identical achievement differences to an average student. Will their self-concepts also share identical differences with the average students' self-concept? Our hypothesis is that students who achieve above average develop self-concepts that are more distinct from average achieving students' self-concepts than are below average achieving students' self-concepts. Sample: In Study 1, N=382 7th-10th graders (62.2% female) from several academic track (Gymnasium) schools in Germany served as participants. Students' ages ranged between 12 and 16 years (M=14.76, SD=6.24). In Study 2, the sample comprised N=1,349 students (49% girls) with a mean age of M=10.87 (SD=0.56) from 60 primary schools that were drawn representatively from a federal German state. In an experimental Study 3, N=81 German teacher education students (76.5% female) aged between 18 and 40 years (M=22.38, SD=3.80) served as participants. Method: Two field studies and one experimental study were conducted. Results: In all three studies, achievement differences between above average and average students were identical to those between average and below average students. However, self-concept differences between above average and average achieving students were greater than those identified between average and below average students. Conclusions: As our studies show, self-enhancement and self-protection processes lead above average students to develop self-concepts that are more distinct from average students' self-concepts than those of below average students' self-concepts.