The aim of this study was to investigate the impact of Socio-Economic Status (SES) on Hebrew-speaking children's developing ability to pluralize nouns and mark adjectives in agreement with them. Participants were 180 gradeschool children from mid-high SES and 180 peers from low SES, in six consecutive grade levels. The task consisted of 32 singular noun-adjective pairs with nouns classified into four categories by suffix type (Regular and Irregular) and by stem type (Nonchanging and Changing). Results showed a consistent advantage to the high SES children in accuracy of noun and adjective plurals, with gaps widening when the morphological requirements were harder, that is, in the irregular categories. Moreover, the fact that low SES children's reaction times to producing the full plural phrase hardly decreased indicates that, unlike their high SES peers, they also did not gain more processing efficiency with age and schooling.