The use of communication strategies (CSs) in oral and written second language (L2) production has been widely investigated (e.g. Muñoz, 2007). As for content and language integrated learning (CLIL) settings, learners seem to resort to the first language (L1) less often than in traditional foreign language instruction (e.g. Celaya & Ruiz de Zarobe, 2010). However, few studies have examined what L2 learners say about their use of CSs by means of questionnaires -- e.g. Ehrman & Oxford (1990), with adult English as a foreign language (EFL) learners -- and little is known about the reported use of CSs by young learners (Purdie & Oliver, 1999), and much less by young CLIL learners. This study examines learners' self-reported opinions about the use of CSs ("guessing," "miming," "morphological creativity," "dictionary," "predicting," "paraphrasing," "borrowing," "calque," "foreignizing," "avoidance" and "appeal for assistance"). An adapted survey (Kellerman, Bongaerts, & Poulisse, 1987; Oxford, 1989; O'Malley & Chamot, 1990; Yule & Tarone, 1990) was administered to CLIL learners of English in grades 5 and 6 of primary education. Quantitative differences in terms of the type of strategies used were explored. Analyses showed striking similarities between grades 5 and 6 as well as significant differences in the use of the different CSs, paraphrasing and appeal for assistance being the most frequent strategies, whereas morphological creativity and miming obtained the lowest frequency. Findings are discussed in the light of learners' age and the nature of CLIL instruction.