Understanding students' college enrollment decisions is critical because the admission outcome can affect the school's quality and its reputation. In this paper, we study how students consider their relative academic ability compared to their potential peers. Drawing from social comparison theory, we posit that there are asymmetric effects due to deviation from peers' ability, depending on the deviations' direction. Using a rich data set of college applicants, we find that while the applicants negatively evaluate their deviations below their potential peers, they value positively those above their peers (the 'big fish, little pond' effect). Moreover, students who applied to many universities are more susceptible to these psychological effects. Further analysis points to the level of the individual student's self-confidence as a possible explanation. Finally, we derive suggestions for college administrators to improve the yield of admitted students.