Up to 16% of students in mainstream secondary schools present with language impairment (LI). As with other learning difficulties, students with LI experience many academic, social, emotional and behavioral problems. Associated presenting behaviors may, however, be masking the primary language impairment. As a result, secondary school students with LI are under-recognised and may therefore be missing out on appropriate supports and services. In order to increase the awareness of education professionals and to increase the likelihood of identification and effective support, this article describes the nature and impact of LI in secondary school student populations. Two hypothetical case studies highlight the educational and psychosocial impact of LI during adolescence.