Vocabulary knowledge has been shown to be a predictor of academic success, posing a challenge for children and young people with language disorder. Language disorder can persist into adolescence and yet there is limited evidence on how to support the vocabulary skills of adolescents with language disorder in a mainstream setting. This article describes an experimental study aimed at investigating the feasibility of a whole-class approach to increase the understanding and use of curriculum vocabulary in adolescents with language disorder. Ten curriculum words were taught by the science teacher using a phonological-semantic approach, and 10 matched same-topic words were taught using routine teaching practice. Progress was made post-intervention in word knowledge of both low-frequency experimental and control words, with significantly greater change in knowledge of the experimental words. Most students, and the teacher, viewed the phonological-semantic word-learning approach favourably.