The aim of the study is to investigate the role of cognitive characteristics (processing speed, working memory and sense of number) and general (nonverbal intelligence) in the individual differences in academic achievement on the samples of high school children from Russia and Kyrgyzstan. These countries are characterized, on the one hand, by similarities in the organization of the national education system, and, on the other hand, differences in socioeconomic status and effectiveness of public education.The study involved 514 schoolchildren at Grades 10 & 11 from two state educational institutions. The samples were balanced by the educational microenvironment. The Russian sample was represented by 205 pupils from 15.8 to 18.8 years (41.9% of boys). The Kyrgyz sample included 309 schoolchildren from 15.3 to 18.8 years (36.4% of boys). It is shown that both in Russia and in Kyrgyzstan, the best model fit was for the speed of information processing as a key predictor of intelligence, working memory and a number sense, which in turn explained variation in the academic achievement. At the same time, we found cross-cultural differences in the interrelationships between certain cognitive development factors and academic achievement. Thus, in less favorable socioeconomic conditions, the greatest functional weight was obtained for the correlation between the speed of processing information and academic achievement through working memory and nonverbal intelligence. On the contrary, under more favorable conditions, the contribution of cognitive characteristics to the development of individual differences in academic achievement was not significant.