In the field of third language acquisition metalinguistic awareness is posited to be a fundamental component of multilingual competence and a key factor facilitating the acquisition of additional languages. Building upon Bialystok's model of attention and control, and Wrembel's research into metaphonological awareness in adult L3 learners, this study examines the role of metalinguistic awareness in the acquisition of Spanish phonology by young instructed L3 learners. The 20 multilinguals (aged 13), who were native speakers of German with upper-intermediate English as their first foreign language and intermediate Spanish as their second foreign language, were subjected to a stimulated recall protocol in German; they were asked to attend to, improve and comment on their own Spanish pronunciation in a reading task from three years ago, i.e. their initial attempts at L3 production. The findings provide evidence for different types and degrees of phonological awareness in the young L3 learners, including intuitive phonological awareness and explicit analyses of primarily Spanish consonants and word stress. Phonological crosslinguistic influence from L2 to L3 appeared to be of special concern to the learners. The findings are discussed from the perspective of both L3 speech learning and teaching. [This paper was presented at the 13th International Conference of the Association for Language Awareness, Vienna, July 2016.]