With the globalisation of education, large numbers of students with interrupted schooling and low English literacy levels represent both a quantitative and qualitative shift in the kinds of students faced by teachers in classrooms. In Australia, after a year in an intensive English language programme, immigrant and refugee students are placed in the mainstream, where they face enormous challenges in content areas such as science. The complexity and specificity of science terminology pose a serious barrier for students. This article reports on a research project to support vocabulary learning in mainstream science for Year 8 refugee students (n = 23) in one high school. Data sources included teacher interviews, student journal writing, and the science text itself. The author demonstrates why science content language is inaccessible to many students through an extensive review of the literature, and then juxtaposes the views of students and teachers with the actual demands of one chapter from the Year 8 Science textbook on states of matter. The final section presents the response of the researchers to help scaffold vocabulary learning for this topic and a trial of the materials. The study highlights the links between conceptual and linguistic understanding. Given that students identified vocabulary as a major barrier to learning, and that the science teacher tended to assume rather than to explain new terminology, the language-focused approach outlined to support vocabulary was seen as one way to address an urgent problem. Implications for professional development and teacher education are also addressed. (Contains 3 tables.)