The article examines the Big-Frog-In-A-Small-Pond Effect, when students, who study in strong schools or classes, have got lower academic self-esteem, than students with the same level of personal achievements, but studying in weaker classes or schools. This effect was considered for self-esteem in math in the longitudinal study of Russian schoolchildren Working and Educational Trajectories, conducted on a Russian sample as a part of international study TIMSS. Also the question of this effect manifesting itself in other educational results was examined: further academic achievements, educational plans and trajectories. The indices of further academic achievements were school marks in algebra and Uniform State Exam results in mathematics. Educational plans were measured by three questions: about aspirations to go to college, estimated probability of choice of STEM profession and estimated points in Uniform State Exam in mathematics. For educational trajectories two indicators were used: continuation of study in general school after the 9th grade and study in a class with enhanced education in math or physics. The results of multilevel regression analysis show that the negative effect of average marks in a class (controlling for the results of TIMSS in math) is important for self-esteem in math, further school marks on algebra and aspirations to go to college. Besides, it is shown that self-esteem in math is an important predictor of further academic achievements, aspirations and trajectories. Moreover, self-esteem in math is a more important factor for the choice of enhanced math education and estimated probability of choice of STEM profession, than the level of previous mathematic achievements.