It has long been suggested that, in a bilingual setting, the proficiencies achieved in the first (L1) and second (L2) language may have a bearing on a subject's cognitive and, consequently, academic functioning. The study is set in Malta, a country in which Maltese (L1) and English (L2) are learnt simultaneously at school from age 5. It investigates the performance of 1262 students (aged 13) in examinations of Physics and Mathematics against their respective performance in English and Maltese. The results seem to support the "threshold hypothesis", first proposed by Jim Cummins, in that students who were highly proficient in "both" languages best performed in their respective Physics and Mathematics examinations. (Contains 7 tables.)