This paper empirically explores the influence of bilingualism on educational performances. This link has been rigorously explored in a number of countries around the world, but not in Russia. The paper employed a sample of 709 ethnic Tatar school students aged 15–16 (in the ninth grade) in the spring of the year 2010. It found a positive significant impact on school grades based on logistic regressions, and controlling for family background features, school features, psychological traits, health issues, peers, gender, and the influence of the capital city Kazan. Oral bilingual children, who employ Tatar language at home, are more likely to attain the highest grades in literature and chemistry classes, and they have lower likelihoods of getting the lowest grades in Russian language, literature, geometry, and physics. The paper did not find negative effects on school grades due to the use of Tatar at home. Thus, evidence was found in favour of bilingualism and against the assumption of Russian policymakers that bilingualism menaces the knowledge of Russian.