The aim of this study was to verify whether children from low socio-economic status (SES) are victims of stereotype threat. Children in first grade (6 to 7 years old) and third grade (8 to 9 years old) performed Raven's progressive matrices, an intellectual ability test commonly used by psychologists. The test was presented either with the (evaluative) instructions recommended by Raven et al. (1998) or with non evaluative instructions. Children's SES and beliefs concerning differences of abilities at school as a function of SES were also assessed. The results indicated that, as early as first grade, participants believed that children from high SES are better at school than children from low SES. Furthermore, low SES participants' performance on the Raven's matrices was lower in the evaluative condition than in the non evaluative condition. The experimental instructions did not affect high SES participants' performance. The discussion explores implications of these results in the use of standardized tests to assess the intellectual abilities of low SES children. (Contains 1 table and 2 notes.)