Background: It is recognized that children from areas associated with socioeconomic disadvantage are at an increased risk of delayed language development. However, so far research has focused mainly on young children and there has been little investigation into language development in adolescence. Aims: To investigate the language abilities of adolescents from two different socioeconomic areas. The paper aims to determine if a higher proportion of adolescents from an area of socioeconomic disadvantage have low language scores when compared with adolescents from a relatively advantaged area. Methods & Procedures: Six standardized language assessments were used to measure expressive and receptive language skills across vocabulary, syntax and narrative in two cohorts of 13 and 14 year olds: one cohort attending a school in an area of socioeconomic disadvantage (103 participants) and the other cohort attending a school in an area of relative socioeconomic advantage (48 participants). Outcomes & Results: The cohort from the area of disadvantage performed significantly lower than the assessments' normative mean on all measures of language ability. There were significant differences between the two cohorts on four of the six language measures. More adolescents from the school in the area of socioeconomic disadvantage had standardized assessment scores that suggest hitherto undetected language difficulties. Conclusions & Implications: Results suggest that socioeconomic background is associated with language ability in adolescence as measured by standardized tests. In particular, adolescents from an area of socioeconomic disadvantage were at risk of low vocabulary scores. The advantages and disadvantages of using standardized language assessments are discussed and the implications for clinical and educational practice and for school level policies are highlighted. (Contains 5 tables.)