Recent research has documented the academic disadvantage of low social class students, whose performance is impaired by competitive educational practices. Across 2 experiments, we examined whether the pursuit of performance-approach goals (aiming to outperform others) favors the emergence of this achievement gap. We first manipulated low versus high relative social class positions; participants then solved a reasoning test, for which they had been incited (or not) to outperform others. In Experiment 1, carried out among French students, participants primed with a low relative social class obtained a lower performance than those primed with a high relative social class--but only when performance-approach goals had been made salient. Results of Experiment 2 replicated this pattern among American participants. These findings reveal that the pursuit of performance-approach goals can fuel the social class achievement gap. We consider the advantages associated with the experimental manipulation of relative social class, and discuss how educational practices and policies may jeopardize--in an invisible way--the potential of lower social class students.