Laboratory-controlled phonetic training protocols have attested that adults can improve L2 sound perception and production skills (Pruitt et al., 2006; Bradlow, 2008). However, few studies have analysed these protocols from a more pedagogically-oriented perspective (Wang & Munro, 2004). The present study aims at filling this gap by examining the impact of phonetic training on English lexical schwa vowel in primary school learners (aged 12) of English as a foreign language in Spain. Students’ awareness on the nature and occurrence of weak vowels in English was tested by means of a computer-aided perceptual identification task which presented both spliced incorrect full vowels and spliced correct schwas in pre-tonic and post-tonic unstressed syllables in English content words (ago, seven). Two groups of students underwent explicit training in English lexical schwa by means of two distinct phonetic treatments: i) auditory discrimination and identification practice and ii) listen-and-repeat practice. A third group did not undergo explicit training but had a native instructor for English and Science.Pre-test results revealed similar perceptual skills among the three groups tested unfolding a lack of perceptual awareness on the occurrence of weak vowels in English, as all three groups judged both weak and strong vowels in unstressed syllables as correct. In the post-test, all the groups could identify spliced full vowels as incorrect to a larger extent, indicating that both explicit phonetic treatment and exposure to native accent may be boosting awareness on the nature and distribution of a weak vowel in English. In addition, the group having undergone a perception-based training method outscored the other two groups in the post-test, supporting the sustaining effect of perception training procedures on perceptual skills. These findings acknowledge the positive impact of controlled phonetic training on perceptual awareness in classroom settings and contribute to the development of L2 pronunciation teaching and learning. References: Bradlow, A. (2008). Training non-native language sound patterns: Lessons from training Japanese adults on the English /r/ – /l/ contrast. In Hansen Edwards, Jette G. & Mary L. Zampini (eds.), Phonology and Second Language Acquisition. (pp. 287–308) Amsterdam: John Benjamins. Pruitt J. S, Jenkins J. J, Strange W. (2006). Training the perception of Hindi dental and retroflex stops by native speakers of American English and Japanese. Journal of the Acoustical Society of America, 119(3), 1684-96.Wang, X., & Munro, M. J. (2004). Computer-based training for learning English vowel contrasts. System, 32, 539-552.