In studies dealing with language learning strategies in the school context, the variables of proficiency and age are often difficult to isolate since students accumulate more hours of foreign language instruction as they move up from grade to grade. This study aimed to deal with these two variables independently by analysing learning strategy use in three groups of bilingual (Catalan/Spanish) learners of different educational levels and by investigating its relationship with English as a foreign language (EFL) grades by age group. The sample included 402 students in Spain (Catalonia) from 18 classes, distributed as follows: 135 students from Grade 7 to Grade 8 (ages 12 and 13), 186 students from Grade 9 to Grade 10 (ages 14 and 15), and 81 students from Grade 11 to Grade 12 (ages 16 and 17). All students were further classified into four groups according to their school grades in English. Data regarding learning strategy use were elicited through a structured questionnaire specifically developed for students in secondary education and poor-input environments. The results indicated that students in lower grades showed clearer preferences for particular types of strategies than older students, and the relationship between learning strategies and EFL grades was stronger in younger students. The findings have important implications for further research on the roles played by proficiency and age in strategy use. (Contains 5 notes and 6 tables.)