The aim of this study was to assess the effect of family socioeconomic status (SES) and parental education on non-verbal IQ and on the processing of oral and written language, working memory, verbal memory and executive functions in children from different age ranges. A total of 419 Brazilian children aged 6-12 years old, attending public and private schools from Porto Alegre, RS participated in the study. Structural equation analyzes revealed that in the general model (for all ages), the SES contributed to cognitive performance -IQ, verbal memory, working memory, oral and written language and executive functions (28, 19, 36, 28 and 25 %, respectively). SES had stronger effects on younger children (up to nine years old), in most cognitive tasks examined. Probably, after this age, a combination of factors such as schooling, living in other social environments, among others, may mitigate the effects of family socioeconomic status.