Main Article Content
One of the foremost critical challenges that learners may face while learning a foreign language is developing a reliable lexicon and mastering words. Inadequate vocabulary knowledge may put serious barriers within the process of learning a second / foreign language (L2). Thus, students must equip themselves with different strategies to overcome these difficulties. One amongst these strategies that has been heeded by many experts is the use of the first language (L1) translation in learning the vocabulary of L2. However, the effect of this strategy on English as a foreign language (EFL) learners’ vocabulary depth remained under explored. Therefore, the primary purpose of this study is to examine the effect of L1 translation on the depth of vocabulary of EFL learners. To attain this goal, a total of 86 Tunisian students, at the fourth year of Secondary Education level, participated in this project. They were randomly selected and divided into a control group and an experimental group. Two Depth of Vocabulary Knowledge tests were assigned to test the research hypotheses. Data was analyzed using two independent-samples t-tests. The findings of the study showed that the participants within the experimental group, who learnt vocabulary through L1 translation strategies, outperformed their counterparts within the control group, who learnt vocabulary through strategies employing only the target language, in relation to their vocabulary depth.