According to the big-fish-little-pond effect (BFLPE), attending academically selective high schools negatively affects academic self-concept. Does the BFLPE persist after graduation from high school? In two large, representative samples of German high school students (Study 1: 2,306 students, 147 schools; Study 2: 1,758 students, 94 schools), the predictive effects of individual achievement test scores and school grades on math self-concept are very positive, whereas the predictive effects of school-average achievement are negative (the BFLPE). Both studies showed that the BFLPE was substantial at the end of high school and was still substantial 2 years (Study 1) or 4 years (Study 2) later. In addition, because of the highly salient system of school tracks within the German education system, the authors are able to show that negative effects associated with school type (highly academically selective schools, the Gymnasium) were similar--but smaller--than the BFLPE based on school-average achievement. (Contains 2 figures and 4 tables.)