Since for high-schoolers many consequential life choices lie still ahead, it is crucial that their choices suit their abilities. Among other things, students’ misperception of their academic ability can lead to educational misinvestment with potentially severe consequences. While previous research has documented gender differences in the self-perception of academic performance, disparities by socioeconomic status (SES) have not been investigated. This paper redresses the gap. Drawing on the German National Educational Panel Study, I examine disparities in the ability to self-evaluate academic performance by SES. Specifically, I rank school grades and academic self-concepts of 15-year-olds within each class to analyze whether their self-evaluation matches their relative performance in class. My findings indicate that students from disadvantaged families self-evaluate their school performance less accurately than students from high-SES families. This result is particularly strong for Math. Low-SES students whose performance lies two standard deviations below the mean performance overestimate their own performance twice as much as high-SES students. I theorize that and subsequently examine whether differential parental feedback on academic ability is the driving mechanism of these results. The mediation analysis confirms that the higher inaccuracy in the self-perception of ability can be fully attributed to differences in parent-teacher contact, parental involvement with homework, and parental educational aspirations. My study illustrates the interplay of parental feedback and children’s self-perception and indicates that low-SES students suffer from higher inaccuracy in the self-evaluation of their school performance due to less and less informative parental feedback.