© Servicio de Publicaciones. Universidad de Murcia. All rights reserved. IJES, vol. 16 (1), 2016, pp. 75–96 Print ISSN: 1578-7044; Online ISSN: 1989-6131 International Journal of English Studies IJES UNIVERSITY OF MURCIA http://revistas.um.es/ijes Age and type of instruction (CLIC vs. traditional EFL) in lexical development MARÍA PILAR AGUSTÍN-LLACH* Universidad de La Rioja Received: 14/02/2015. Accepted: 3/09/2015. ABSTRACT The present paper compares the vocabulary development of a group of CLIL and of traditional EFL learners along three years. The observation that a CLIL approach might provide with larger benefits in the long run vocabulary is the starting point of this study. We had learners in the two groups complete a letter-writing task. These writings were then scrutinized for L1 influence in the form of borrowings and lexical creations. The frequency of the words in the letters was also object of analysis. Results revealed that CLIL learners perform slightly better but non-significantly better than traditional EFL along the three years. Furthermore, the evolution of L1 influence and word use also followed an expected improvement pattern as learners went up grade. However, our results do not provide evidence of a growing CLIL advantage with increasing experience. The young age and low proficiency of learners in the present study might be blocking this possible advantage found elsewhere. KEYWORDS: type of instruction, CLIL vs. EFL, age constraints, vocabulary acquisition, L1 influence. 1. INTRODUCTION The observation that Content and Language Integrated Learning, henceforth CLIL, is better in the long run and that its effects start becoming visible after some experience with the approach (cf. Celaya & Ruiz de Zarobe, 2010; Pfenninger, 2014), sustains the present research. This claim is, therefore, the starting point of our study. Specifically, we looked at the production of borrowings and L1 influenced lexical creations which have been identified to change their patterns of appearance as learners gain in proficiency and get older (e.g. Celaya, 2008). We wonder, thus, how the evolution of borrowings and lexical creations _____________________ *Address for correspondence: María Pilar Agustín-Llach. Universidad de La Rioja, Dpto. Filologías Modernas, C/ San José de Calasanz, 33, 26004, Logroño, La Rioja, Spain; e-mail: maria-del-pilar.agustin@unirioja.es.