Competitiveness and cooperativeness are important predictors of social and learning outcomes at school. Drawing on evidence suggesting that contexts with high income inequality foster an ethos of competitiveness and inhibit cooperativeness in the economic environment, we examine whether income inequality is also associated with more competitiveness and less cooperativeness in the academic environment. We conducted four preregistered studies to test this idea. In Study 1, analysis of the OECD PISA 2018 data set (≈500,000 15-year-old students from 75 countries) revealed that students from economically unequal countries perceive their schoolmates as more competitive and less cooperative. In Study 2a and 2b, analysis of the PISA 2003 (250,000 + students from 38 countries) and PISA 2000 (75,000 + students from 32 countries) data sets revealed that students from unequal countries are themselves more competitive and, surprisingly, also more cooperative. Follow-up analyses resolved this apparent paradox, showing that students from unequal countries are oriented toward instrumental rather than intrinsic cooperativeness (i.e., using cooperation as a strategic tool to achieve academic success rather than for the enjoyment of the activity itself). Study 3 offers a conceptual experimental replication (≈850 young adults imagining going back to school) and indicates that induced income inequality (a) increases perceived competitiveness, (b) decreases perceived cooperativeness, (c) prompts an orientation toward competitiveness, and (d) prompts an orientation toward instrumental rather than intrinsic cooperativeness. Results are discussed in relation to the multidisciplinary literatures on the psychology of income inequality, the selective function of school systems, coopetition, self-determination, and cooperative learning.